Muwatta Malik 498

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنِ ابْنِ شِهَابٍ، عَنْ أَبِي عُبَيْدٍ، مَوْلَى ابْنِ أَزْهَرَ عَنْ أَبِي هُرَيْرَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏ "‏ يُسْتَجَابُ لأَحَدِكُمْ مَا لَمْ يَعْجَلْ فَيَقُولُ قَدْ دَعَوْتُ فَلَمْ يُسْتَجَبْ لِي ‏"‏ ‏.‏

Yahya related to me from Malik from Ibn Shihab from Abu Ubayd, the mawla of Ibn Azhar, from Abu Hurayra that the Messenger of Allah, may Allah bless him and grant him peace, said, "You will be answered as long as you are not impatient and say, 'I have made a dua and I have not been answered

Reference

Muwatta Malik 498

In-book

Book 15, Hadith 29