(a) Mu'awiyah bin Qurrah (may Allah have mercy on him) says: I had two paternal uncles, both of whom were present at the Tree (among the Companions of the Tree, may Allah be pleased with them), and both used to trim their moustaches and nails every Friday. (b) It is reported from Sayyiduna Abdullah bin Abbas (may Allah be pleased with him), attributed to the Prophet: "The believer on every Friday is like one in ihram; he does not trim his hair or clip his nails until the prayer is completed." (c) It is reported from Sayyiduna Abdullah bin Umar (may Allah be pleased with him), attributed to the Prophet: "The Muslim on Friday is in a state of ihram; when he has prayed, he leaves it."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجمعة / 5965