I say, and with God's success: Yes, the laughter of a conscious adult praying who bows and prostrates nullifies the ablution. The limit of laughter is what is audible to him and his neighbors, whether his teeth are visible or not. It invalidates both the ablution and the prayer, whether he laughed intentionally or forgetfully, whether he was in a state of ablution or performing dry ablution, and it does not invalidate the purity of the full ablution. As for laughing, which is what is audible to him but not to his neighbors, it invalidates the prayer but not the ablution. As for smiling, which is not audible to him or others, it does not invalidate either the prayer or the ablution. The analogy is that laughter should not be considered an event in prayer, but we left the analogy; due to what Al-Daraqutni reported in his Sunan from Anas, may God be pleased with him: "The Messenger of God, peace be upon him, was praying with us when a blind man came and stepped into a mess on the ground, and he fell, and some of the people laughed. The Messenger of God, peace be upon him, commanded those who laughed to repeat their ablution and prayer." And from Abu Al-Layth, may God have mercy on him: "A blind man fell into a well while the Prophet, peace be upon him, was praying with his companions, and those who were praying with him laughed, so he commanded those who laughed to repeat their ablution and prayer," in the Sunan of Al-Bayhaqi Al-Kabir 2: 252, and the Musannaf of Abdul Razzaq 2: 376, and the Musannaf of Ibn Abi Shaybah 1: 341, and the Marasil of Abu Dawood p. 75, and Al-Kamil 3: 167, and the History of Jurjan 1: 405. And Al-Laknawi said after mentioning the chains of the hadiths regarding laughter: These authentic hadiths and the transmitted reports clearly indicate that ablution is invalidated by laughter. Whoever wishes to delve into the hadith narrations regarding the nullification of ablution by laughter should refer to "Al-Hassasa on the Nullification of Ablution by Laughter" by Al-Laknawi, and I'la Al-Sunan 1: 132-144, and God knows best.