It is sunnah to make the takbir upon every rising, lowering, standing or sitting, except when one comes up from bowing, in which case one should say, “Allah hears him who praises Him.” Reported Ibn Mas’ud, “I saw the Messenger of Allah make the takbir upon every lowering, rising, standing and sitting.” This is related by Ahmad, an-Nasa’i and at-Tirmizhi, who called it shaih.
Says at-Tirmizhi, “The companions of the Prophet, upon whom be peace, including Abu Bakr, ‘Umar, ‘Uthman, ‘Ali and others, acted according to this hadith, as did their followers and the majority of the jurists and scholars.” Abu Bakr ibn ‘Abdurahman ibn al-Harith reported that he heard Abu Hurairah say, “When the Prophet, upon whom be peace, stood for prayer, he would make the takbir while standing. Then he made the takbir while bowing. When coming up from the bowing, he would say, “Sami’Allahu liman hamidah (Allah hears him who praises Him). While standing, he would say, “Rabbana lakal-hamd (Our Lord, to You is the praise).” Then he would say, “Allahu akbar” when he would go down for the prostration, when he raised his head, and when he stood from his sitting after the two prostrations. He did that in every rak’ah until he finished the prayer. He prayed in that manner until he left this world.” (Related by Ahmad, al-Bukhari, Muslim and Abu Dawud.)
‘Ikrimah said to Ibn ‘Abbas, “I prayed the noon prayer in al-Butha behind a foolish old man. He would make twelve takbirs by saying it when he prostrated and when he raised his head.” Ibn ‘Abbas said, “That is the prayer of Abu al-Qasim (the Prophet).” (Related by Ahmad and al-Bukhari.) It is preferable to start the takbir when one begins one’s changing of position.