Sayyiduna Abdullah bin Salam (may Allah be pleased with him) said: When the Messenger of Allah (peace and blessings be upon him) arrived in Madinah, the people were waiting for him. When he arrived, the people said: The Messenger of Allah has come, the Messenger of Allah has come. Hearing this, I also came out with the other people, and when I saw the blessed face of the Prophet (peace and blessings be upon him), I became certain that his face was not the face of a liar (i.e., he could not be a liar). The very first thing I heard from him at that time was: "O people! Spread the greeting of peace, feed others, maintain ties of kinship, and pray at night when people are asleep; you will enter Paradise in peace."
Hadith Referenceسنن دارمي / من كتاب الصللاة / 1499