Which prophet asked the Messenger to lighten the prayer?

The Prophet who asked the Messenger of Allah, peace and blessings be upon him, to request a reduction from his Lord was Musa (Moses), peace be upon him. This is based on what is authentically narrated in the Two Sahihs from the hadith of Anas ibn Malik, where Musa said: "Go back to your Lord and ask Him for a reduction, for your Ummah (nation) will not be able to bear that."