Raising the hands when standing up after two rak'ahs

Nafi' said: When Ibn Umar (may Allah be pleased with them both) began the prayer, he would say the takbir and raise his hands; when he bowed, he would also raise his hands; when he said 'Sami'a Allahu liman hamidah' (Allah has heard the one who praised Him), he would also raise his hands; and when he stood up from two rak'ahs, he would also raise his hands. And Ibn Umar (may Allah be pleased with them both) narrated this hadith as marfu' (attributed) to the Prophet (peace and blessings be upon him).
Abd al-A'la is alone in attributing it to the Prophet (peace and blessings be upon him), and he is thiqah (trustworthy).

Muhammad bin Amr bin Ata said: I heard Abu Humayd (may Allah be pleased with him) say: When the Messenger of Allah (peace and blessings be upon him) stood for the prayer, he would face the qiblah and raise both hands level with his shoulders, then say 'Allahu Akbar' (Allah is the Greatest). When he bowed, he would also say the takbir and raise his hands; then he would level his back, neither lowering his head too much nor raising it too high. Then he would raise his head and say 'Sami'a Allahu liman hamidah' (Allah has heard the one who praised Him). Then he would raise his hands level with his shoulders, then stand up straight until every limb settled evenly in its place. Then he would do the same in the second rak'ah, until, when he stood up from two rak'ahs, he would say the takbir and raise his hands just as he (peace and blessings be upon him) had raised them at the beginning of the prayer; until, when he was in the last prostration of the last rak'ah, after which the salam is given, he would raise his head from the prostration and sit in tawarruk, that is, he would keep the right foot upright and bring the left foot out to the right side from beneath the right leg.

Muhammad bin Amr bin Ata (may Allah have mercy on him) said: I heard Sayyiduna Abu Humayd al-Sa'idi (may Allah be pleased with him), while sitting among ten Companions of the Messenger of Allah (peace and blessings be upon him), among whom was Sayyiduna Abu Qatadah al-Harith bin Rib'i (may Allah be pleased with him), say: "I know more than all of you about the prayer of the Messenger of Allah (peace and blessings be upon him)." It also contains that he (peace and blessings be upon him) would raise both his hands level with his shoulders when he began the prayer, when he bowed, and when he rose from bowing. Then, when he stood up after two rak'ahs, he would say the takbir and raise both hands to his shoulders, just as he raised them with the takbir at the beginning of the prayer. Then he would do the same in the rest of his prayer.

It is narrated from Sayyiduna Ali bin Abi Talib (may Allah be pleased with him) that when the Messenger of Allah (peace and blessings be upon him) stood for the obligatory prayer, he would say the takbir and raise both hands to his shoulders; when he completed the recitation and intended to bow, he would also do so; when he raised his head from bowing, he would do the same; he would not raise his hands while in the sitting position; and when he stood up from the two prostrations, he would say the takbir and raise his hands in the same way.