Ammar, the freed slave of Banu Hashim, narrates from Sayyiduna Abu Hurayrah (may Allah be pleased with him). Ali reported it as marfu' (attributed to the Prophet), while Yunus did not go beyond Sayyiduna Abu Hurayrah (may Allah be pleased with him). Concerning the words "And by the witness and the witnessed" [Surah al-Buruj: 3], he said: "'The witness' means the day of Jumu'ah and of Arafah, and 'the witnessed' means the Day of Resurrection, the day that has been promised."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجمعة / 5563