هل هو إلا بضعة منه؟
Is it not simply a part of his body?
A report discusses touching a bodily organ by comparing it to other kinds of contact with one's own body. The reasoning is that bodily contact alone is not necessarily an effective cause of invalidating ablution in every case.
Legal lesson: Where other texts address the particular act, a jurist cannot settle the matter by saying only 'this too is touching'. All relevant evidence must be examined to see which attribute the law actually treats as operative.
Schools differ over the detailed ablution ruling; this slide explains the analogical reasoning in the reported example.