Urging the call to Allah the Exalted and mentioning the qualities of the caller: First: that he be knowledgeable in accordance with the Book and the Sunnah.

The Shaykh : However, it is obligatory that, along with this, we be callers like our righteous predecessors, callers whose actions are followed before their words are taken, such that each of us possesses a great deal of knowledge, intellect, worship, asceticism, and good character. The call cannot have any effect unless these qualities are present. If an ignorant person wants to be a caller, he may say falsehood without knowing it, or he may remain silent about the truth without knowing it. Therefore, knowledge is necessary, but where do we receive knowledge?
We receive knowledge from two primary sources: the Book of Allah and the Sunnah of His Messenger (peace and blessings be upon him), according to the understanding of the Companions and those who followed them in excellence, and the imams of guidance, not according to an understanding based on deviant opinions, religious innovations, and misguidance.