the Musnad is a report from ʿAdī ibn Hātim, graded authentic by al-Tirmidhī, explaining this verse:
“When he asked the Prophet, may Allah bless him and grant him peace, about it, he said, ‘They did not worship them.’ The Prophet, may Allah bless him and grant him peace, replied, ‘They made lawful for them what was forbidden and forbade them what was lawful, and they obeyed them. That was their worship of them.’”
Hence it has been said of such people: “They deprived themselves of attainment by neglecting the foundations.” For the most fundamental foundation is to truly believe in what the Messenger, may Allah bless him and grant him peace, brought. One must therefore believe in Allah, His Messenger, and what His Messenger, may Allah bless him and grant him peace, brought. One must believe that Muhammad, may Allah bless him and grant him peace, is Allah’s Messenger to all creation: humans and jinn, Arabs and non-Arabs, scholars and worshippers, kings and common people. No created being has any path to Allah, Mighty and Majestic, except by following him inwardly and outwardly. Indeed, had Moses, Jesus, or any other prophet lived to see his mission, they would have been obliged to follow him. As Allah, Most High, says:
“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 have, 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.’”
“Then whoever turns away after that—it is they who are defiantly disobedient.”
Ibn ʿAbbās, may Allah be pleased with them both, said: “Allah never sent a prophet without taking his covenant that, if Muhammad were sent while he was still alive, he would surely believe in him and support him. He also commanded him to take his people’s covenant that, if Muhammad were sent while they were still alive, they would surely believe in him and support him.” And He has said