(a) It is narrated from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both): I saw the Messenger of Allah (peace and blessings be upon him). When he (peace and blessings be upon him) stood in the prayer, he raised both hands level with his shoulders and said the takbir. Then, when he said the takbir for the bowing, he did the same, and when he raised his head from the bowing he also did the same and said: 'Sami' Allahu liman hamidah' (Allah Almighty hears the one who praises Him). He did not do this in the prostrations.
Ibn al-Mubarak (may Allah have mercy on him) used to raise his hands in the five prayers, the voluntary prayers, the two Eid prayers and the funeral prayer.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2504