Silsilat al-Ahadith al-Sahihah

It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "These things are from the nature (fitrah) of Islam: taking a bath on Friday, using the miswak, trimming the moustache, and letting the beard grow, because the Magian people let their moustaches grow and shave their beards, so you should oppose them and trim the moustaches and let the beards grow."