John Gill Commentary Mark 6:39

"And he commanded them that all should sit down by companies upon the green grass." — Mark 6:39 (ASV)

And he commanded them to make all sit down
Christ ordered his disciples, without any more ado, to cause the whole multitude, men, women, and children, to sit, or lie down, as they used to do at table when about to take a meal: and as they had no table before them, nor beds, or couches to sit, or lie down upon, he directed them to place them

by companies upon the green grass ;
that there might be some order among them, as at a meal; and that their number might be the more easily known; and that all of them might more plainly see the miracle that was to be wrought: and the provision be more orderly distributed to them.