Abu al-Bakhtari (may Allah have mercy on him) relates: We sighted the new moon of Dhu al-Hijjah as a large moon; the one who estimated less said it was two nights old, and the one who estimated more said it was three nights old. Then when we reached Makkah, I met Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) and asked him about the Day of Tarwiyah, and he counted it for me from that day (of sighting). I said: "But we saw the moon as large." He said: "The Prophet (peace and blessings be upon him) extended its period up to its sighting."
Imam al-Tabarani (may Allah have mercy on him) said: "No one narrated this hadith from Abu Khalid al-Dalani except Abd al-Salam bin Harb. And Shu'bah has also narrated it from Amr bin Murrah."
Hadith Referenceالمعجم الأوسط / باب الألف / 2228
Hadith Takhrij«أخرجه الدارقطني فى «سننه» برقم: 2208»