Ibn ‘Umar (may Allah be pleased with him and his father) reported:
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, when saying Takbīr (proclaiming Allah's greatness) for Rukū‘ (bowing), and when raising his head from Rukū‘ he would raise them as well and say: "Sami‘allāhu liman hamidah, rabbana wa laka al-hamd" (Allah hears whoever praises Him, O our Lord, praise be to You). He did not use to do this in Sujūd (prostration).
Reported by Al-Bukhari (No. 735, 736), Muslim (No. 390a, 390b), Abu Dawud (No. 721, 722, 742), At-Tirmidhi (No. 255, 256), An-Nasa’i (No. 877, 878, 1025, 1057, 1059, 1088, 1144), Ibn Majah (No. 858), Malik (No. 167), Ahmad (No. 4312, 4445, 4837, 5027, 5502, 5899) and Ad-Darimi (No. 1222).
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.
Lessons
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.
Explanation in Arabic
كانَ النبيُّ صلى الله عليه وسلم يرفع يديه في ثلاثةِ مواضع من الصلاة إزاء أو مقابل المنكب الذي هو: مجمع عظم الكتف والعضد.
الموضع الأول: إذا افتتح الصلاة عند تكبيرة الإحرام.
الثاني: إذا كبّر للركوع.
الثالث: إذا رفع رأسه من الركوع وقال: سمع الله لمن حمده ربنا ولك الحمد.
وكان لا يرفع يديه عند ابتداء السجود، ولا عند الرفع منه.
من حِكَم رفع اليدين في الصلاة أنها زينة للصلاة وتعظيم لله سبحانه.
ثبت عنه صلى الله عليه وسلم رفع يديه في موضع رابع كما في رواية أبي حميد الساعدي عند أبي داود وغيره، وهو عند القيام من التشهد الأول في الصلاة الثلاثية والرباعية.
ثبت عنه صلى الله عليه وسلم أيضًا أنه يرفع يديه حذو أذنيه دون لمس كما في رواية مالك بن الحويرث في الصحيحين: «أن رسول الله صلى الله عليه وسلم كان إذا كبر رفع يديه حتى يحاذي بهما أذنيه».
الجمع بين التسميع والتحميد خاص بالإمام والمنفرد، أما المأموم فيقول: ربنا ولك الحمد.
قول: "رَبَّنَا وَلَكَ الحَمْدُ" بعد الركوع صح عن النبي صلى الله عليه وسلم فيه أربع صيغ، وهذه واحدة منها، والأفضل أن يتتبع المرء هذه الصيغ ويأتي بهذا مرة، وهذه مرة.
Mālik ibn al-Huwayrith (may Allah be pleased with him) reported: When the Messenger of Allah (may Allah's peace and blessings be upon him) made Takbīr, he would raise his hands up to the level of his ears. When he bowed, he would raise his hands up to the level of his ears, and when he raised his…
Mutarrif ibn ‘Abdullāh reported: I prayed with ‘Imrān ibn Husayn behind ‘Ali ibn Abi Tālib. When he prostrated, he made Takbīr, when he raised his head he made Takbīr, and when he stood up after two Rak‘ahs, he made Takbīr. After he had finished praying, ‘Imrān took my hand and said: "This reminded…