When should one raise one's hands when rising from bowing (ruku') to stand upright?

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When rising from bowing and straightening up to a standing position, one should say 'Sami'a Allahu liman hamidah' (Allah hears those who praise Him). The raising of the hands should occur either after fully straightening up and attaining stillness, or concurrently when beginning to raise the head from bowing. The first opinion, supported by Imam Ahmad ibn Hanbal, holds that the hands are not raised until one is completely upright, citing a narration from Ibn Umar where the Prophet, peace be upon him, raised his hands after raising his head from bowing. The second opinion holds that raising the hands begins when the raising of the head starts, based on narrations from Abu Hamid and Ibn Umar indicating the Prophet, peace be upon him, raised his hands when starting the rise, as this is a transitional movement like entering ruku'.