Sayyiduna Abdullah bin Unays (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: "I was shown Laylat al-Qadr, then I was made to forget it, and I was shown that on the morning after it I was prostrating in water and mud." The narrator says: It rained on us on the twenty-third night, and he (peace and blessings be upon him) led us in prayer; then when he (peace and blessings be upon him) turned away, the traces of water and mud were on his (peace and blessings be upon him) nose and forehead. And Sayyiduna Abdullah bin Unays (may Allah be pleased with him) used to say that it is the twenty-third night.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصيام / 8536