How many times may Muslims deliver Dawa lectures to non-Muslims who show no interest in the message?

There is no specific number of lectures; rather, it depends on the number of locations, the available time, and the level of public engagement. The caller to Islam should be wise and choose the appropriate time and place, and not despair from repeating the call, for conveying the message is his duty, and Allah guides whom He wills. The call should be accompanied by a smile, mercy, and a sincere desire to save those being invited. If possible, the caller should offer financial assistance or help solve their problems, as this prepares hearts. Allah Almighty said: (Nor can goodness and evil be equal. Repel (evil) with what is better: then verily he, between whom and you was enmity, (will become) as though he was a warm friend). It is also necessary to leave da‘wah materials (leaflets, booklets) with those being invited so that they can read them in the absence of the caller. And employers should be advised to be kind to their workers, as this enhances their acceptance of Islam.