Muslim records the ḥadīth of al-ʿAbbās b. ʿAbdu’l-Muṭṭalib (RA) that Allāh’s Messenger (SAW) said, “Someone who is pleased with Allāh as his Lord, Islām as his religion, and Muḥammad as his Prophet will have tasted the sweetness of faith.”
To be pleased and content with Allāh means to be happy with Him and to delight in His Lordship over you, His regulation of your affairs and His decree. To be pleased and content with Islām as religion means to be happy with it, and to praise Allāh for this immense favour. Allāh has chosen you for Islām, conferred this religion on you and granted you the divine accord to live by it. Being pleased and content with Muḥammad (SAW) as Prophet means to believe that he is the most perfect of creation, personifying the peak of every lofty quality and trait. It also means to believe that his nation is the best of nations, having the highest ranking in this life and the Hereafter. Being pleased with the Prophethood of the Messenger (SAW), his message and his followers is one of the greatest factors that lead to faith flourishing and tasting its sweetness.
Allāh says, “Allāh showed great kindness to the believers when He sent a Messenger to them from among themselves to recite His Signs to them, purify them and teach them the Book and Wisdom, even though before that they were clearly misguided” (Q3:164) “A Messenger has come to you from among yourselves. Your suffering is distressing to him; he is deeply concerned for you; he is gentle and merciful to the believers.” (Q9:128)
How can the believer not be pleased with this noble, gentle, merciful Messenger? Allāh Himself has taken an oath stating that he has an exalted standard of character. How can he not love him and follow him? Loving him is a sign of loving Allāh, and through following him does one perfect this love and faith, “Say: If you love Allāh, follow me, Allāh will love you and forgive you your sins.” (Q3:31)