Genesis 35:22

35:22 While Israel was living in that land, Reuben had sexual relations with ¹  Bilhah, his father’s concubine, and Israel heard about it.

Jacob had twelve sons:

Genesis 42:22

42:22 Reuben said to them, “Didn’t I say to you, ‘Don’t sin against the boy,’ but you wouldn’t listen? So now we must pay for shedding his blood!” ² 

¹ tn Heb “and Reuben went and lay with.” The expression “lay with” is a euphemism for having sexual intercourse.

² tn Heb “and also his blood, look, it is required.” God requires compensation, as it were, from those who shed innocent blood (see Gen 9:6). In other words, God exacts punishment for the crime of murder.