Now that the disposition of the Holy Prophetsa had settled and calmed, he began to invite people to the unity of God, the Most High, and propogated teachings against polytheism. In the beginning, the Holy Prophetsa did not preach his mission openly; rather, he began this process with extreme silence and kept his teachings confined to his close circle of friends.1
1 * Sharḥul-‘Allāmatiz-Zarqānī ‘alal-Mawāhibil-Ladunniyyah, By Muḥammad bin ‘Abdul-Bāqī Az-Zarqānī, Volume 1, p. 461, Bābul-Ijhāri bi Da‘watihī, Dārul-Kutubil-‘Ilmiyyah, Beirut, Lebanon, First Edition (1996)
* Tārīkhuṭ-Ṭabarī, By Abū Ja‘far Muḥammad bin Al-Jarīr Ṭabarī, Volume 2, p. 221, Bābu Dhikril-Khabri ‘ammā kāna min Amrin-Nabīsa ‘inda Ibtidā’illāhi Ta‘ālā, Dārul-Fikr, Beirut, Lebanon, Second Edition (2002)