Another interpretation, ben Azzai says: One mitzva leads to another mitzva, and one sin leads to another sin. How is this so? It is written previously: “When you go out to war…and you see in the captivity [a beautiful woman]…” (Deuteronomy 21:10–11). The Holy One blessed be He said: ‘Although I permitted her to you, I said to you: “She shall shave her head, and she shall grow her nails,” (Deuteronomy 21:12), so that she should not find favor in your eyes and you send her away.
If you did not do so, what is written thereafter? “If a man will have a defiant and rebellious son” (Deuteronomy 21:18). And as a result of that, “if there will be in a man a sin with a death sentence”’ (Deuteronomy 21:22). This shows that one sin leads to another sin.
One mitzva leads to another mitzva – from where is it derived? “If a bird's nest will happen before you” (Deuteronomy 22:6). As a result [of following this mitzva], “when you build a new house [you shall make a parapet for your roof]” (Deuteronomy 22:8). And as a [further] result [of following the mitzva, you will have a vineyard, and] “you shall not sow your vineyard with diverse kinds” (Deuteronomy 22:9).
And as a [further] result [of following the mitzva, you will have a field, and] “you shall not plow with an ox and a donkey together” (Deuteronomy 22:10). And as a [further] result [of following the mitzva, you will have clothing, and] “You shall make for you twisted threads [on the four corners of your garment]” (Deuteronomy 22:12). This shows that one mitzva leads to another mitzva.