1)
Why did they swear?
1.
Malbim: It was so that one who transgressed the Bris would be punished (die). Due to the Shevu'ah, people would fear to transgress even in private.
Why did they swear?
Malbim: It was so that one who transgressed the Bris would be punished (die). Due to the Shevu'ah, people would fear to transgress even in private.