Numbers 2:14

Then the tribe of Gad
Who was placed on the other side of Reuben's standard, and according to the former direction he must be before, and Simeon behind; and Gad being the eldest son of Leah's handmaid Zilpah, is fitly placed under Leah's firstborn, and being the son of an handmaid, could not object to his situation:

and the captain of the sons of Gad [shall be] Eliasaph the son of
Reuel:
who is called Deuel, ( Numbers 1:14 ) ( 7:42 ) . The letters (r) , "resh", and (d) , "daleth", being similar, are sometimes put one for the other, of which there are other instances, as in ( Genesis 10:3 Genesis 10:4 ) , compared with ( 1 Chronicles 1:6 1 Chronicles 1:7 ) .