Hazrat Shaikh Moulana Muhammad Zakariyya (rahmatullahi ‘alaih) mentioned in Fazaail-e-Aa’maal:
There are many verses of the Quraan Majeed and many ahaadeeth which mention that the Malaaikah (angels) remain perpetually engaged in ‘ibaadah (the worship of Allah Ta‘ala). The ahaadeeth mention that there is a group of angels who are such that they perpetually remain in rukoo’, and they will remain in rukoo’ until Qiyaamah. Then, there is another group who perpetually remain in sajdah, and there is another group who perpetually remain in qiyaam.
Allah Ta‘ala has honoured the believer in this way that He has combined all these postures in two rakaats of salaah, so that we may get a share from each form of worship of the angels. Reciting the Quraan Majeed in salaah is an extra act of worship, over and above their type of ‘ibaadah.
When salaah is the combination of all the various forms of worship of the angels, then the beauty of the salaah will be easily acquired by the one who adopts the qualities of the angels.
It is for this reason that Rasulullah (sallallahu ‘alaihi wasallam) said, “Keep your back and stomach light for salaah.” The meaning of “keeping the back light” is that a person leaves all disputes behind him, and it is clear that the meaning of “keeping the stomach light” is that one should not overeat, as this creates lethargy and laziness.
(Fazaail-e-Aa’maal [Urdu] pg. 375)
Source: Ihyaauddeen.co.za