Sayyiduna Malik bin Huwairith (may Allah be pleased with him) narrates: We came to the service of the Prophet Muhammad (peace be upon him). We were young men of similar age. We stayed with him for twenty days. When he realized that we were missing our families, he asked us what we had left behind for our families. We informed him about this. The Prophet Muhammad (peace be upon him) was very kind and soft-hearted. He said: Go back to your families, stay with them, teach them, and command them, and perform the prayer as you have seen me performing the prayer. When the time for prayer comes, let one of you give the call to prayer (adhan), and let the eldest among you lead the prayer. (Imam Ibn Hibban, may Allah have mercy on him, says:) The statement of the Prophet Muhammad (peace be upon him), "Perform the prayer as you have seen me performing it," is a command that includes everything the Prophet (peace be upon him) used to do during the prayer. However, among those things which have been declared optional (nafl) by consensus or by another hadith, there is no harm for the one who leaves them during the prayer. But those things which have not been specified as optional by consensus or hadith, all addressed individuals are obliged to perform them, and it is not permissible to leave them under any circumstances.