פירוש על ברכות 46:13

Viz. the probability of soiling the hand with urine.

As follows: An occasional privy is not to be treated as strictly as a regular one; if then we are permitted to hold the Tefillin in the latter, how much more so in the former! This is irrefutable as an argument, but it nevertheless leads to a wrong conclusion. We have consequently to base our position on the practical consideration of the possibility of soiling the hand.