Is it permissible for a داعية (caller to Islam) who travels for da‘wah (proselytizing) at the expense of da‘wah funds to perform personal tasks in those areas? And is the acceptance by a داعية or a طالب علم (student of sacred knowledge) of travel expenses for da‘wah or learning considered as taking a wage for da‘wah or for teaching sacred knowledge?

It is permissible for a preacher who travels at the expense of a da'wah institution to carry out some of his private tasks, as long as the money is not spent for purposes other than what it was allocated for, or the destination is not chosen for personal reasons. If these impediments are absent, then there is no harm, just as Allah permitted trade for the pilgrim. As for taking travel expenses for da'wah or seeking knowledge, it is not a payment for them, but rather a form of seeking assistance for righteousness and obedience, and Allah commanded cooperation in righteousness and piety.