Riyad as-Salihin, Book 18, Hadith 1789 (In-Book) ⓘ

Abu Bakrah (May Allah be pleased with him) reported: Mention of a man was made to the Prophet and someone praised him whereupon he said, "Woe be to you! You have broken the neck of your friend!" He repeated this several times and added, "If one of you has to praise his friend at all, he should say: 'I reckon him to be such and such and Allah knows him well', if you think him to be so-and-so, you will be accountable to Allah because no one can testify the purity of others against Allah."[Al-Bukhari and Muslim].

وعن أبي بكر رضي الله عنه أن رجلا ذُكر عند النبي صلى الله عليه وسلم ، فأثنى عليه رجل خيرًا، فقال النبي صلى الله عليه وسلم ‏:‏ ‏"‏ويحك‏!‏ قطعت عنق صاحبك‏"‏ يقوله مرارًا ‏"‏وإن كان أحدكم مادحًا لا محالة، فليقل‏:‏ أحسب كذا وكذا إن كان يرى أنه كذلك وحسيبه الله، ولا يزكي على الله أحدًا‏"‏ ‏(‏‏(‏متفق عليه‏)‏‏)‏‏.‏