A study of the meanings of the verse "So pray to your Lord and sacrifice"

As for the words of Allah, the Mighty and Majestic: "So pray to your Lord and sacrifice" [Surah al-Kawthar: 2], the Companions (may Allah be pleased with them) differed in its explanation and interpretation, and the best statement among them is what has been narrated from the Commander of the Believers, Sayyiduna Ali bin Abi Talib (may Allah be pleased with him), in two narrations, the first of which is this:

It is narrated from Sayyiduna Ali (may Allah be pleased with him) concerning "So pray to your Lord and sacrifice" [Surah al-Kawthar: 2], that he said: "This refers to your placing your right hand upon your left in the prayer."
And the second narration is this:

It is narrated from Sayyiduna Ali bin Abi Talib (may Allah be pleased with him) that he said: When this verse was revealed to the Messenger of Allah (peace and blessings be upon him): "Indeed, We have given you al-Kawthar. So pray to your Lord and sacrifice" [Surah al-Kawthar: 1-2], the Prophet (peace and blessings be upon him) asked Jibril (peace be upon him): "What is this sacrifice that my Lord has commanded me?" He said: "It is not a sacrifice; rather, He commands you that when you begin the prayer with the opening takbir, you raise both your hands when saying the takbir, and (raise them) also when you bow and when you raise your head from bowing, for this is our prayer and the prayer of the angels who are in the seven heavens." The Prophet (peace and blessings be upon him) said: "Raising the hands is part of the humility about which Allah Almighty said: 'But they did not humble themselves before their Lord, nor do they supplicate humbly' [Surah al-Mu'minun: 76]."