وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ زَيْدِ بْنِ أَسْلَمَ، أَنَّهُ كَانَ يَقُولُ مَا مِنْ دَاعٍ يَدْعُو إِلاَّ كَانَ بَيْنَ إِحْدَى ثَلاَثٍ إِمَّا أَنْ يُسْتَجَابَ لَهُ وَإِمَّا أَنْ يُدَّخَرَ لَهُ وَإِمَّا أَنْ يُكَفَّرَ عَنْهُ ‏.‏

Yahya related to me from Malik that Zayd ibn Aslam used to say,"No-one makes a dua without one of three things happening. Either itis answered, or it is stored up for him, or wrong actions are atonedfor by it." Translation Not Available

Book Ref: Muwatta Imam Malik Book 15 Hadith 508
Web Ref:  Muwatta Imam Malik Book 15 Hadith 36