“do not look down on any act of kindness, even if it is meeting your brother with a cheerful face.” Reported by Muslim.

Explanation
Imam al-Nawawī, may Allah have mercy on him, cited these hadiths in Riyāḍ al-Ṣāliḥīn under the chapter on the etiquette of shaking hands, embracing, and related matters. Among them is the report of Ṣafwān ibn ʿAssāl (may Allah be pleased with him): a Jewish man said to his companion, “Let us go to this man,” meaning the Prophet ﷺ. They went to him, questioned him, and the Prophet ﷺ mentioned nine clear signs. Thereupon they kissed his hand and his foot and declared, “We bear witness that you are a Prophet.”

The Jews were living in Medina. Their forefathers had originally been in Egypt among the Children of Israel, then they moved to al-Sham, to the Holy Land about which their Prophet Moses, peace be upon him, said, “My people, enter the Holy Land that Allah has prescribed for you.” They read in the Torah that a Prophet would be sent at the end of time, that he would come from Mecca, and that his migration would be to Medina. So many of them migrated from al-Sham to Medina, waiting for the Prophet ﷺ so that they might follow him, for his merit had been extolled in both the Torah and the Gospel. Allah the Exalted says: “Those who follow the Messenger, the unlettered Prophet, whom they find written…” (Q 7:157).