ENOfficial
Abu Hurayra reported that the Messenger of Allah, may Allah bless him and grant him peace, said, "The supplication of any of you is answered as long as he does not get impatient and say, 'I made supplication and was not answered.'"
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا أَبُو الْيَمَانِ، قَالَ: حَدَّثَنَا شُعَيْبٌ، عَنِ الزُّهْرِيِّ قَالَ: أَخْبَرَنِي ابْنُ عُبَيْدٍ مَوْلَى عَبْدِ الرَّحْمَنِ، وَكَانَ مِنَ الْقُرَّاءِ وَأَهْلِ الْفِقْهِ، أَنَّهُ سَمِعَ أَبَا هُرَيْرَةَ، أَنَّ رَسُولَ اللهِ صلى الله عليه وسلم قَالَ: يُسْتَجَابُ لأَحَدِكُمْ مَا لَمْ يَعْجَلْ، يَقُولُ: دَعَوْتُ فَلَمْ يُسْتَجَبْ لِي.
sunnah.com