Must a son abandon daʿwah work in an Islamic group if his father orders him to do so and threatens him with ostracism and displeasure?

Working to serve the religion of Allah is obligatory, and cooperating in it is essential. Pleasing one's parents is a religious obligation, and through it one attains the pleasure of Allah. Therefore, be keen to please your father and persuade him to help you in working for the religion of Allah, and ensure the soundness of your work and methodology. Seek help from people of knowledge whose opinions he respects to speak with him. If he is affected by scaremongering campaigns, inform him that a Muslim who fortifies himself with adhkar (remembrances of Allah) and is diligent in performing the Fajr prayer in congregation is under the protection of Allah, and there is no fear for him. If he insists on severing ties with you, then be keen to gain his satisfaction, and reach an understanding with him to work in fields about which he has no fears. Increase your supplications to Allah to grant you success in combining the pleasure of your father with serving your religion, and to grant you success in cooperating with people of good. The soundness and clarity of the methodology must be emphasized.