Adam Clarke on Joshua 24:25

Joshua made a covenant - Literally, Joshua cut the covenant, alluding to the sacrifice offered on the occasion.

And set then a statute and an ordinance - He made a solemn and public act of the whole, which was signed and witnessed by himself and the people, in the presence of Jehovah; and having done so, he wrote the words of the covenant in the book of the law of God, probably in some part of the skin constituting the great roll, on which the laws of God were written, and of which there were some blank columns to spare. Having done this, he took a great stone and set it up under an oak - that this might be עד ed or witness that, at such a time and place, this covenant was made, the terms of which might be found written in the book of the law, which was laid up beside the ark. See Deu 31:26.