the Rock and subsequently commanded us to face the Kaaba, each of these two acts was part of Islam when He commanded it. Religion consists in obedience to Him and worship of Him in both acts; only an outward aspect of the act varies, namely, the direction faced in prayer. Likewise, the messengers’ religion is one, even though their laws, prescribed ways, prayer directions, and rites differ. Such differences do not prevent their religion from being one, just as they did not prevent this within the law of a single messenger.

Allah Most High made it part of the messengers’ religion that the first of them should announce the coming of the last and believe in him, and that the last should affirm the truth of the first and believe in him. Allah Most High said:

“And when Allah took the covenant of the prophets: ‘Whatever I give you of Scripture and wisdom, should a messenger then come to you confirming what you possess, you must believe in him and support him.’ He said, ‘Do you acknowledge this and accept My binding covenant?’ They said, ‘We acknowledge it.’ He said, ‘Then bear witness, and I am with you among the witnesses.’”

Ibn ‘Abbās said: Allah never sent a prophet without taking a covenant from him that, if Muhammad were sent while he was still alive, he would believe in him and support him. He also commanded him to take a covenant from his people that, if Muhammad were sent while they were still alive, they would believe in him and support him.

Allah Most High also said:

“And We have revealed to you the Scripture in truth, confirming the Scripture that came before it and standing as a guardian over it. So judge between them by what Allah has revealed, and do not follow their desires, turning away from the truth that has come to you. To each of you We have prescribed a law and a way.”

He made belief in any of the messengers inseparable from belief in the others, and declared anyone who claimed to believe in some and disbelieve in others to be a disbeliever.