What is meant by advice to Allah and His Messenger, mentioned in the noble Hadith, “Religion is advice”?

The Hadith "Religion is sincerity (nasiha)" means that religion is sincerity to Allah, to His Book, to His Messenger, to the leaders of the Muslims, and to their common folk. Sincerity to Allah: is to affirm His Oneness, to glorify Him, and to obey Him. To His Book: is to believe in it, to recite it as it should be recited, to act upon it, and to call others to it. To His Messenger: is to believe in him, to honor him, to revive his Sunnah, and to follow his morals. To the leaders of the Muslims: is to assist them in truth, to obey them in it, to remind them gently, and to supplicate for their rectification. To the common folk of the Muslims: is to guide them to their interests, to teach them their religion, to conceal their faults, to support them, and to love goodness for them.