The Call of the Messengers Revolves around Three Things
Imām Ibn Al-Qayyim, may Allāh have mercy on him, said:
Indeed, the call of the Messengers revolves around three matters: [the first is] making Al-Rabb [the Single, Absolute Lord of all Creation] known to those being called, through His names, attributes, and actions.
The second foundation is [getting them] to know the path that reaches Him: remembering Him [on one’s tongue and in one’s heart], showing gratitude to Him, and worshiping Him, [a worship] that combines a completeness of love for Him with a completeness of abject servility to Him.
The third foundation is informing them about what is [in store] for them—after reaching Him in His place of honor—of pleasures, the best and greatest of which is His being pleased with them; His showing Himself to them; their seeing His face, high above all; His greeting them with salām; and His speaking to them.
Al-Ṣawāʾiq Al-Mursalah, vol. 4, p. 1489.