Hadith Q1019
وَوَضْعِ الْيَدِ عَلَى الْأَنْفِ كَيْ يُتَوَهَّمَ النَّاسُ أَنَّهُ رَاعِفٌ لَا مُحْدِثٌ حَدَثًا مِنْ دُبُرٍ
And the statement about placing the hand on the nose so that other worshippers think that he has a nosebleed, not that wind has passed from him.
Hadith 1019
Lady Aisha (may Allah be pleased with her) narrates from the Noble Prophet (peace and blessings be upon him) that he said: "When the ablution of any one of you breaks during prayer, he should place his hand on his nose and leave the prayer."