The Highest Iman is Shahada - Prophet Muhammad ﷺ (Muttafaqun ʿAlayhi – Sahih Al-Bukhari & Sahih Muslim collection)

OverView of Shahada - The Highest Iman

Faith(Iman) has over seventy branches or over sixty branches, the most excellent of which is the declaration that there is nothing worthy of worship in truth except Allah, and the humblest of which is the, removal of what is injurious from the path: and modesty is a branch of faith. - Sahih Al-Bukhai Hadith 9 & Sahih Muslim Hadith 35 (Muttafaqun ʿAlayhi).