Abu Uthman said: I prayed the morning prayer behind Sayyiduna Umar (may Allah be pleased with him). He recited eighty verses of Surah al-Baqarah, recited the qunut after the bowing and raised his hands, until I saw the whiteness of his (may Allah be pleased with him) armpits. He was supplicating in a loud voice, so much so that a man on the other side of the wall could hear it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3149