Sahl ibn Hanif was one of the most sincere and bravest companions of the Prophet of Islam (PBUH) and Imam Ali (AS). He participated in all the wars with the Prophet (PBUH), and was very handsome and his beautiful face was well known among people. It is narrated about him: He was with the Prophet (PBUH) in one of the wars, and reached a river, washed himself in it and and one of the people who saw him out of surprise said a sentence about him, after which he became very ill with fever. He was taken to the Prophet (PBUH); after asking about him, the Prophet (PBUH) said: What will happen if you find a good thing about the body or wealth/property of your brother; say God bless/May God bless you? Because evil eye is real (it is the truth). Then the prophet (PBUH) recommended in these cases, pray for the intended person .
 Safinatul Behar, Vol. 1, Page 676.