John Gill Commentary Numbers 36:5

"And Moses commanded the children of Israel according to the word of Jehovah, saying, The tribe of the sons of Joseph speaketh right." — Numbers 36:5 (ASV)

And Moses commanded the children of Israel
Even all the tribes of Israel, whom the following law concerned, as well as the tribe of Manasseh:

according to the word of the Lord ;
whom no doubt he consulted on this occasion, as he did when the daughters of Zelophehad applied to him about the inheritance of their father:

saying, the tribe of the sons of Joseph has said well ;
in showing such a concern for the welfare of their tribe; the consideration of which would be of service to them all, and therefore was worthy of notice. Aben Ezra observes, that the heads of the fathers spoke for the sake of every tribe, what was for the good of them all, and therefore was well spoken.