Swear no oath
Swear no oath
We should not forswear ourselves. As Jesus talks about in Mt 5:33-37.
(Matthew 5:33-37 [KJV])  Again, ye have heard that it hath been said by them of old time, Thou shalt not forswear thyself, but shalt perform unto the Lord thine oaths:  But I say unto you, Swear not at all; neither by heaven; for it is God’s throne:  Nor by the earth; for it is his footstool: neither by Jerusalem; for it is the city of the great King.  Neither shalt thou swear by thy head, because thou canst not make one hair white or black.  But let your communication be, Yea, yea; Nay, nay: for whatsoever is more than these cometh of evil.
This is also what Joshua did in Joshua 9 when he made a league with the men that had the mouldy bread, the inhabitants of Gibeon (Joshua 9:15).
King James Version (1769) with Strongs Numbers and Morphology: Joshua Chapter 9  And it came to pass, when all the kings which were on this side Jordan, in the hills, and in the valleys, and in all the coasts of the great sea over against Lebanon, the Hittite, and the Amorite, the Canaanite, the Perizzite, the Hivite, and the Jebusite, heard thereof;  That they gathered themselves together, to fight with Joshua and with Israel, with one accord.  And when the inhabitants of Gibeon heard what Joshua had done unto Jericho and to Ai,  They did work wilily, and went and made as if they had been ambassadors, and took old sacks upon their asses, and wine bottles, old, and rent, and bound up;  And old shoes and clouted upon their feet, and old garments upon them; and all the bread of their provision was dry and mouldy.  And they went to Joshua unto the camp at Gilgal, and said unto him, and to the men of Israel, We be come from a far country: now therefore make ye a league with us.  And the men of Israel said unto the Hivites, Peradventure ye dwell among us; and how shall we make a league with you?  And they said unto Joshua, We are thy servants. And Joshua said unto them, Who are ye? and from whence come ye?  And they said unto him, From a very far country thy servants are come because of the name of the LORD thy God: for we have heard the fame of him, and all that he did in Egypt,  And all that he did to the two kings of the Amorites, that were beyond Jordan, to Sihon king of Heshbon, and to Og king of Bashan, which was at Ashtaroth.  Wherefore our elders and all the inhabitants of our country spake to us, saying, Take victuals with you for the journey, and go to meet them, and say unto them, We are your servants: therefore now make ye a league with us.  This our bread we took hot for our provision out of our houses on the day we came forth to go unto you; but now, behold, it is dry, and it is mouldy:  And these bottles of wine, which we filled, were new; and, behold, they be rent: and these our garments and our shoes are become old by reason of the very long journey.  And the men took of their victuals, and asked not counsel at the mouth of the LORD.  And Joshua made peace with them, and made a league with them, to let them live: and the princes of the congregation sware unto them.  And it came to pass at the end of three days after they had made a league with them, that they heard that they were their neighbours, and that they dwelt among them.  And the children of Israel journeyed, and came unto their cities on the third day. Now their cities were Gibeon, and Chephirah, and Beeroth, and Kirjath–jearim.  And the children of Israel smote them not, because the princes of the congregation had sworn unto them by the LORD God of Israel. And all the congregation murmured against the princes.  But all the princes said unto all the congregation, We have sworn unto them by the LORD God of Israel: now therefore we may not touch them.  This we will do to them; we will even let them live, lest wrath be upon us, because of the oath which we sware unto them.  And the princes said unto them, Let them live; but let them be hewers of wood and drawers of water unto all the congregation; as the princes had promised them.  And Joshua called for them, and he spake unto them, saying, Wherefore have ye beguiled us, saying, We are very far from you; when ye dwell among us?  Now therefore ye are cursed, and there shall none of you be freed from being bondmen, and hewers of wood and drawers of water for the house of my God.  And they answered Joshua, and said, Because it was certainly told thy servants, how that the LORD thy God commanded his servant Moses to give you all the land, and to destroy all the inhabitants of the land from before you, therefore we were sore afraid of our lives because of you, and have done this thing.  And now, behold, we are in thine hand: as it seemeth good and right unto thee to do unto us, do.  And so did he unto them, and delivered them out of the hand of the children of Israel, that they slew them not.  And Joshua made them that day hewers of wood and drawers of water for the congregation, and for the altar of the LORD, even unto this day, in the place which he should choose.
Interesting enough in Judges 2:2-3 it says that they made a league with the people and therefore God made sure that "their gods shall be a snare unto you"
King James Version (1769) with Strongs Numbers and Morphology: Judges Chapter 2  And an angel of the LORD came up from Gilgal to Bochim, and said, I made you to go up out of Egypt, and have brought you unto the land which I sware unto your fathers; and I said, I will never break my covenant with you.  And ye shall make no league with the inhabitants of this land; ye shall throw down their altars: but ye have not obeyed my voice: why have ye done this?  Wherefore I also said, I will not drive them out from before you; but they shall be as thorns in your sides, and their gods shall be a snare unto you.  And it came to pass, when the angel of the LORD spake these words unto all the children of Israel, that the people lifted up their voice, and wept.  And they called the name of that place Bochim: and they sacrificed there unto the LORD.  And when Joshua had let the people go, the children of Israel went every man unto his inheritance to possess the land.  And the people served the LORD all the days of Joshua, and all the days of the elders that outlived Joshua, who had seen all the great works of the LORD, that he did for Israel.  And Joshua the son of Nun, the servant of the LORD, died, being an hundred and ten years old.  And they buried him in the border of his inheritance in Timnath–heres, in the mount of Ephraim, on the north side of the hill Gaash.  And also all that generation were gathered unto their fathers: and there arose another generation after them, which knew not the LORD, nor yet the works which he had done for Israel.  And the children of Israel did evil in the sight of the LORD, and served Baalim:  And they forsook the LORD God of their fathers, which brought them out of the land of Egypt, and followed other gods, of the gods of the people that were round about them, and bowed themselves unto them, and provoked the LORD to anger.  And they forsook the LORD, and served Baal and Ashtaroth.  And the anger of the LORD was hot against Israel, and he delivered them into the hands of spoilers that spoiled them, and he sold them into the hands of their enemies round about, so that they could not any longer stand before their enemies.  Whithersoever they went out, the hand of the LORD was against them for evil, as the LORD had said, and as the LORD had sworn unto them: and they were greatly distressed.  Nevertheless the LORD raised up judges, which delivered them out of the hand of those that spoiled them.  And yet they would not hearken unto their judges, but they went a whoring after other gods, and bowed themselves unto them: they turned quickly out of the way which their fathers walked in, obeying the commandments of the LORD; but they did not so.  And when the LORD raised them up judges, then the LORD was with the judge, and delivered them out of the hand of their enemies all the days of the judge: for it repented the LORD because of their groanings by reason of them that oppressed them and vexed them.  And it came to pass, when the judge was dead, that they returned, and corrupted themselves more than their fathers, in following other gods to serve them, and to bow down unto them; they ceased not from their own doings, nor from their stubborn way.  And the anger of the LORD was hot against Israel; and he said, Because that this people hath transgressed my covenant which I commanded their fathers, and have not hearkened unto my voice;  I also will not henceforth drive out any from before them of the nations which Joshua left when he died:  That through them I may prove Israel, whether they will keep the way of the LORD to walk therein, as their fathers did keep it, or not.  Therefore the LORD left those nations, without driving them out hastily; neither delivered he them into the hand of Joshua.