Is it permissible for a man to look at a man with lust, and how is the Companions' looking at the Prophet, describing him, praising him, contemplating his face, and their approval of that, to be explained?

A man is permitted to look at another man's body parts that are not considered 'awrah, as long as it is not with lust. However, if there is a fear of temptation (fitna), such as looking at a beautiful beardless youth, then it is absolutely impermissible to look, whether with lust or without it. The Companions' gaze at the Prophet, peace and blessings be upon him, was out of love, respect, and eagerness to observe his image and hear his words, not lust. It is not permissible to harbor such a thought about them.