The ruling on going out for da'wah (calling others to Islam) for a set period of three days or forty days

Question:
Another questioner says: What is your opinion of people who go out to call people to Allah and set a time limit for it, such as three days or forty days, with the intention of calling people to Allah and reforming the people?

Answer:
Calling people to Allah is required, but we do not accept conditions that a person sets up on his own. The Messenger (peace and blessings be upon him) called people to Allah, and the callers to Allah after the Messenger did not have these conventions of forty days, four months, or the like. These are invalid conditions that they devised on their own. Calling people to Allah is an act of worship, and it is not permissible for anything to occur in it for which there is no evidence from the Sunnah of the Messenger (peace and blessings be upon him). Yes.