I say, and with God's guidance: His ablution is not invalidated, but the prayer is only nullified; because it is a condition for laughter that invalidates ablution to occur during a prayer that includes bowing and prostration; and the funeral prayer has neither bowing nor prostration; and because the text here is contrary to analogy, it is limited to its specific case, which is the unrestricted prayer, so it is limited to it, and thus it does not constitute an event in other prayers; Al-Daraqutni reported in his Sunan from Anas : "The Messenger of Allah  was praying with us, when a blind man came and stepped into a filth on the ground, and fell, and some of the people laughed, so the Messenger of Allah صلى الله عليه وسلم ordered those who laughed to redo their ablution and prayer." See: Sharh Al-Waqayah, 2: 33-34, and Tabyin Al-Haqaiq, 1/ 11, and Fath Bab Al-Inayah, 1/ 68, and Al-Ikhtiyar, 1/16-17, and Mukhtalif Al-Riwayah, p.344-345, and Allah knows best.