From Sahih Muslim (Hadith 7502):
Abd al-Rahman b. Abu Bakra reported on the authority of his father that a person was mentioned in the presence of Allah's Apostle (ﷺ), and a person said:Allah's Messenger, no person is more excellent than he after Allah's Messenger (ﷺ). Thereupon Allah's Apostle (ﷺ) said: Woe be to thee, you have broken the neck of your friend, and he said this twice. Then Allah's Messenger (ﷺ) said: If anyone has to praise his brother at all, he should say: I think him to be so and so, and even on this he should say: I do not consider anyone purer than Allah (considers)
Reference: Muslim 7502