"you shall not lie down with his pledge": You shall not lie down with his pledge in your possession.
(Ibid. 13) "Return shall you return to him the pledge when the sun sets": And elsewhere (Shemoth 22:25) "until the sun sets (in the daytime) shall you return it to him." We are hereby taught that he returns to him what is used during the day in the daytime, and what is used at night, in the evening — a mattress in the evening and a plow in the daytime, and not the reverse.
"and he shall bless you": We are hereby taught that he is commanded to bless you. I might think that if he blessed you, you will be blessed; and if not, not. It is, therefore, written "and for you it will be righteousness before the L-rd your G-d."