Musnad Abu Ya'la al-Mawsili 153:5

Abu Khaythama narrated to us, Ibn 'Uyaynah narrated to us, from al-Zuhri, from Salim, from his father, who said: A man saw that the Night of Decree (Laylat al-Qadr) is the night of the twenty-seventh. The Prophet, may Allah bless him and grant him peace, said: "I see your visions in the last ten [nights], so seek it in the odd-numbered ones among them."