Swear

The great take away here is that "swearing" is not just a mere verbal sound being made, but rather a decisive act, namely to "seven oneselves", meaning to repeat something 7 times to give effect and affirmation thereto.

שׁבע shâba H7650. It is denominated by the word seven.

Abraham swears and uses 7 ewes as witness

Genesis 21:22 And it came to pass at that time, that Abimelech and Phichol the chief captain of his host spake unto Abraham, saying, God [is] with thee in all that thou doest:

Genesis 21:23 Now therefore swear unto me here by God that thou wilt not deal falsely with me, nor with my son, nor with my son’s son: [but] according to the kindness that I have done unto thee, thou shalt do unto me, and to the land wherein thou hast sojourned.

Genesis 21:24 And Abraham said, I will swear.

Genesis 21:25 And Abraham reproved Abimelech because of a well of water, which Abimelech’s servants had violently taken away.

Genesis 21:26 And Abimelech said, I wot not who hath done this thing: neither didst thou tell me, neither yet heard I [of it], but to day.

Genesis 21:27 And Abraham took sheep and oxen, and gave them unto Abimelech; and both of them made a covenant.

Genesis 21:28 And Abraham set seven ewe lambs of the flock by themselves.

• picking them out and preserving them separately (holy)

Genesis 21:29 And Abimelech said unto Abraham, What [mean] these seven ewe lambs which thou hast set by themselves?

Genesis 21:30 And he said, For [these] seven ewe lambs shalt thou take of my hand, that they may be a witness unto me, that I have digged this well.

Genesis 21:31 Wherefore he called that place Beersheba; because there they sware both of them.

Genesis 21:32 Thus they made a covenant at Beersheba: then Abimelech rose up, and Phichol the chief captain of his host, and they returned into the land of the Philistines.

Genesis 21:33 And [Abraham] planted a grove in Beersheba, and called there on the name of the LORD, the everlasting God.

Ezekiel

Ezekiel 21:23 And it shall be unto them as a false divination in their sight, to them that have sworn oaths: but he will call to remembrance the iniquity, that they may be taken.