Kommentar zu Bamidbar 1:12

לדן, “of Dan;” he is mentioned first among the four sons of the concubines, as he was the firstborn among them. Asher is mentioned next to him, as his tribe was the leading one in the group of tribes encamped around his flag. (Numbers 2,27) This is followed by Gad, who was the firstborn son of Leah’s servant maid.