The Messenger of Allah (may Allah's peace and blessings be upon him) used to raise his hands in line with his shoulders when commencing the prayer,

Explanation

The Prophet (may Allah's peace and blessings be upon him) used to raise his hands to be parallel with or in alignment with the shoulder, which is the part where the shoulder and upper arm bones are connected, in three positions during the prayer. First position: When commencing the prayer and making Takbīrat al-Ihrām (Opening Takbīr). Second: When making Takbīr for Rukū‘. Third: When raising his head from Rukū‘ and saying: Sami‘allāhu liman hamidah, rabbana wa laka al-hamd" (Allah hears whoever praises Him, O our Lord, praise be to You). He would not raise his hands upon making Sujūd or rising therefrom.

Benefits

• One of the rationales behind raising the hands in prayer is that it is an adornment for the prayer and glorification of Allah Almighty.
• It was proven from the Prophet (may Allah's peace and blessings be upon him) that he raised his hands in a fourth position, as reported in the version of Abu Humayd as-Sā‘idi by Abu Dāwūd and others, upon rising from the first Tashahhud in the three-Rak‘ah and four-Rak‘ah prayers.
• It was also authentically reported from the Prophet (may Allah's peace and blessings be upon him) that he used to raise his hands in alignment with his ears without touching them, as reported in the version of Mālik ibn al-Huwayrith in the Two Sahīh Collections: "When making Takbīr, the Messenger of Allah (may Allah's peace and blessings be upon him) would raise his hands until they were in line with his ears."
• Coupling Tasmī‘ (saying: Allah hears whoever praises Him) with Tahmīd (saying: O our Lord, praise be to You) is exclusive for the Imam and the one praying alone. However, the one praying behind the Imam should only say: "Rabbana wa laka al-hamd" (O our Lord, praise be to You).
• Four wordings were authentically reported from the Prophet (may Allah's peace and blessings be upon him) regarding the way of saying: "Rabbana wa laka al-hamd" (O our Lord, praise be to You) after Rukū‘ and this is one of them. It is preferable that one follows these wordings and uses them alternately.