It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that once the Prophet (peace and blessings be upon him) observed i'tikaf during the last ten days of Ramadan: a tent made of palm branches was set up for the Prophet (peace and blessings be upon him). One day, the Prophet (peace and blessings be upon him) put his head out from it and said: Whoever stands to pray is in fact supplicating to his Lord, so you should know what you are supplicating to your Lord. And do not recite aloud over one another in prayer.