I say, and with God's success: it does not invalidate the ablution; for Qais ibn Talq said, my father told me, "We were with the Prophet (peace be upon him) when a Bedouin came to him and said: O Messenger of God (peace be upon him), if one of us is in prayer and he touches himself, does that invalidate his prayer?" The Messenger of God (peace be upon him) said: "Is it not just a part of you or a piece of you?" This is narrated in Sahih Ibn Hibban 3: 403, and the wording is his, and in Al-Muntaka 1: 18, Al-Mujtabi 1: 101, Musannaf Ibn Abi Shaybah 1: 152, Musannaf Abdul Razzaq 1: 118, and Sharh Ma'ani Al-Athar 1: 118. See also: Majma' Al-Zawa'id 1: 244. And see: Al-Wiqayah p. 91, and Kanz Al-Daqaiq 1: 12, and God knows best.