The Prophet ﷺ heard a man praising another man and he was exaggerating in his praise. The Prophet ﷺ said (to him). "You have destroyed (or cut) the back of the man."  

سَمِعَ النَّبِيُّ ﷺ رَجُلاً يُثْنِي عَلَى رَجُلٍ وَيُطْرِيهِ فِي الْمِدْحَةِ فَقَالَ أَهْلَكْتُمْ أَوْ قَطَعْتُمْ ظَهْرَ الرَّجُلِ  

A man was mentioned before the Prophet ﷺ and another man praised him greatly The Prophet ﷺ said, "May Allah's Mercy be on you ! You have cut the neck of your friend." The Prophet ﷺ repeated this sentence many times and said, "If it is indispensable for anyone of you to praise someone, then he should say, 'I think that he is so-and-so," if he really thinks that he is such. Allah is the One Who will take his accounts (as He knows his reality) and no-one can sanctify anybody before Allah." (Khalid said, "Woe to you," instead of "Allah's Mercy be on you.")  

أَنَّ رَجُلاً ذُكِرَ عِنْدَ النَّبِيِّ ﷺ فَأَثْنَى عَلَيْهِ رَجُلٌ خَيْرًا فَقَالَ النَّبِيُّ ﷺ وَيْحَكَ قَطَعْتَ عُنُقَ صَاحِبِكَ يَقُولُهُ مِرَارًا إِنْ كَانَ أَحَدُكُمْ مَادِحًا لاَ مَحَالَةَ فَلْيَقُلْ أَحْسِبُ كَذَا وَكَذَا إِنْ كَانَ يُرَى أَنَّهُ كَذَلِكَ وَحَسِيبُهُ اللَّهُ وَلاَ يُزَكِّي عَلَى اللَّهِ أَحَدًا قَالَ وُهَيْبٌ عَنْ خَالِدٍ وَيْلَكَ