´An-Nu'man bin Bashir said:` "I am the most knowledgeable among the people about the prescribed time of this prayer: Allah's Messenger would pray it when the moon set on the third (of the month)."
Hadith ReferenceSunan at-Tirmidhi / The Book on Salat (Prayer) / Hadith: 165
Hadith Gradingالألبانی:صحيح، المشكاة (613) ، صحيح أبي داود (445)