Friday instead, and forbade gathering on Saturday.
Whoever abandoned the law of Moses before it was abrogated was not a Muslim, and whoever fails to enter the law of Muhammad—may Allah bless him and grant him peace—after it has superseded the earlier dispensation is likewise not a Muslim.
Allah has never legislated for any prophet that he worship anyone other than Him—ever. The Exalted says:
“He has ordained for you in religion what He enjoined upon Noah, and what We have revealed to you, and what We enjoined upon Abraham, Moses, and Jesus: ‘Establish the religion and do not divide therein.’ What you call the polytheists to burdens them greatly.” (Qur’an 42:13)
Thus He commanded the messengers to establish the religion and not to fall into division.
He, the Most High, also says:
“O messengers, eat of the good things and act righteously; I am fully aware of what you do. Truly, this community of yours is a single community, and I am your Lord, so fear Me.” (Qur’an 23:51–52)
And He says:
“So set your face toward the religion, turning solely to Allah—the natural disposition upon which He created mankind. There is no changing the creation of Allah; that is the upright religion, though most people do not know—turning to Him in repentance, fearing Him, and establishing prayer. Do not be of those who associate others with Him, those who have split up their religion and become factions, each party rejoicing in what it has.” (Qur’an 30:30–32)
The people of idolatry are divided, whereas the people of pure devotion are united. Allah, the Exalted, says:
“They will not cease to differ, except those upon whom your Lord has mercy—and for that He created them.” (Qur’an 11:118–119)
Those who are shown mercy are united and gathered together; the idolaters have fragmented their religion and become sects.