John Gill Commentary Mark 10:4

"And they said, Moses suffered to write a bill of divorcement, and to put her away." — Mark 10:4 (ASV)

And they said

By way of reply,

Moses suffered to write a bill of divorcement, and to put her away

Moses did not command them to divorce their wives, only suffered them to do so: and gave orders that if they could not bear that they should live with them, but would divorce them, that they should give them a bill, which should certify, they were so divorced, and then send them out of their houses, free to marry other men; this law, or permission, is in (Deuteronomy 24:1) , of the form of a bill of divorcement, (See Gill on Matthew 5:31).