Shaykh Saalih Al Fawzaan said:
“As for that which they name now “Khurooj” (as the tableeghis claim when they go out for “Dawah”), then this is an innovation. It has not been reported from the Salaf.
A person going out calling to Allah is not restricted to specific days. Rather, he calls to Allah in accordance to his capability, without restricting that to a group, or forty days or lesser or more than that (i.e. forty days).
Similarly that which is obligatory upon the caller is that he posses knowledge. It is not permissible for a person to call to Allah whilst he is ignorant.
Allah Ta’alaa says
قُلْ هَـذِهِ سَبِيلِي أَدْعُو إِلَى اللّهِ عَلَى بَصِيرَةٍ
Say Oh Muhammad: this is my path I call to Allah upon insight
Meaning upon knowledge, because the caller must know what to call to from that which is obligatory, recommended, prohibited or disliked.
He must also know that which is Shirk, sin, disbelief, and evil deeds.
He must also know the levels of forbidding and how it is done.
Going out for Dawah which busies one from seeking knowledge is a false action, because seeking knowledge is obligatory and it isn’t attained except by way of learning. It is not attained by way of inspiration. This is from the superstitions of the misguided Sufis.
Actions without knowledge is misguidance, and desiring to attain knowledge without learning is a mistaken illusion.
[Al Muntaqaa 1/67]
Majid Jawed Al-Afghanee