Authentic Supplication Number 65.

It is reported by way of ‘Abdillah bin ‘Umar  that a man said: O’ Messenger of Allah! The Mu’ath-thineen are of greater virtue than we are, so the Messenger of Allah  said: “Say as they say, when you have finished, then ask and you shall be granted it”.

Reported by Abu Dawood. Al-Albani said it was of comely ascription and that Ibn Hibban said it was sound. It is #58 in The Authentic of Good Sayings.