Al-Adab Al-Mufrad, Book 16, Hadith 333 (English) ⓘ

Abu Bakr reported that a man was mentioned in the presence of the Prophet, may Allah bless him and grant him peace, and someone praised him. The Prophet, may Allah bless him and grant him peace, said, "Woe to you! You have cut off the head of your companion!" and he repeated that several times. He went on, "If one of you must praise someone, he should say, 'I consider that so-and-so is such-and-such.' Allah is the One who will take account of him if he thinks that he is indeed like that, No one can appropriate Allah's right to attest to someone's character."

حَدَّثَنَا مُحَمَّدٍ، قَالَ‏:‏ حَدَّثَنَا آدَمُ، قَالَ‏:‏ حَدَّثَنَا شُعْبَةُ، عَنْ خَالِدٍ، عَنْ عَبْدِ الرَّحْمَنِ بْنِ أَبِي بَكْرَةَ، عَنْ أَبِيهِ، أَنَّ رَجُلاً ذُكِرَ عِنْدَ النَّبِيِّ صلى الله عليه وسلم فَأَثْنَى عَلَيْهِ رَجُلٌ خَيْرًا، فَقَالَ النَّبِيُّ صلى الله عليه وسلم‏:‏ وَيْحَكَ قَطَعْتَ عُنُقَ صَاحِبِكَ، يَقُولُهُ مِرَارًا، إِنْ كَانَ أَحَدُكُمْ مَادِحًا لاَ مَحَالَةَ فَلْيَقُلْ‏:‏ أَحْسَبُ كَذَا وَكَذَا، إِنْ كَانَ يَرَى أَنَّهُ كَذَلِكَ، وَحَسِيبُهُ اللَّهُ، وَلاَ يُزَكِّي عَلَى اللهِ أَحَدًا‏.‏