It is narrated from Sayyiduna Abu Malik al-Ash'ari (may Allah be pleased with him) that during the Farewell Hajj, in the middle of the days of sacrifice, the Messenger of Allah (peace and blessings be upon him) said: "Is this not the sacred day?" They said: Indeed it is, O Messenger of Allah. He (peace and blessings be upon him) said: "Then the sanctity between you until the Day of Resurrection is like the sanctity of this day." Then he said: "Shall I not tell you who the Muslim is? The one from whose tongue the Muslims are safe. And shall I tell you who the believer is? The one whom the believers trust with their lives and their blood. And shall I tell you who the emigrant (muhajir) is? The one who has abandoned sins and abandoned what Allah has forbidden. The believer is sacred to the believer like the sanctity of this day: his flesh is forbidden to him, that he should eat it and backbite him in his absence; his honour is forbidden to him, that he should tear it; his face is forbidden to him, that he should slap it; and it is forbidden to him to push him in a way that causes him hardship."
Hadith Referenceالمعجم الكبير للطبراني / باب الحاء / 3449