John Gill Commentary Genesis 30:18

"And Leah said, God hath given me my hire, because I gave my handmaid to my husband: and she called his name Issachar." — Genesis 30:18 (ASV)

And Leah said, God has given me my hire Of the mandrakes with which she had hired of Rachel a night's lodging with Jacob, and for which she had a sufficient recompense, by the son that God had given her: and she added another reason, and a very preposterous one, and shows that she put a wrong construction on the blessing she received: because I have given my maiden to my husband; which she judged was so well pleasing to God, that he had rewarded her with another son; and she called his name Issachar, which signifies "hire" or "reward"; or, there is a reward, or a man of reward.