It is narrated from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that when he began the prayer he raised both hands, and when he bowed or rose from the bowing, and when he rose after two rak'ahs, he raised his hands at all of these points. Abdullah bin Umar (may Allah be pleased with them both) attributed this to the Prophet (peace and blessings be upon him) as a marfu' report.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2509