Abstinence, when used as birth control, still looks like commission to me (although the concept of 'commission' isn't the most well-defined of terms).

Suppose that you would have sex in the hypothetical case that you were sterile. Then, in the real world where you aren't sterile, renouncing sex in favour of sleeping doesn't seem any less of a 'commission' than putting a latex barrier between your genitals while you have sex.