How can an elderly preacher, who has work and family obligations, balance memorizing the Qur’an and learning the necessary religious knowledge for his da‘wah, given the time constraints?

The ranks of knowledge and acts of worship vary, and when they conflict, the more important takes precedence over the important. One begins by learning religious obligations, such as the pillars of faith (Iman) and Islam, and this becomes more emphasized with old age. After that, one strives to learn the Book of Allah, even if it is just one verse daily, to combine beneficial knowledge, righteous deeds, and calling to Allah. The differences in people's natures and circumstances are taken into account when determining what is best for each individual. This matter requires consultation with people of knowledge and religion, and Allah's guidance. Ibn Taymiyyah said: "Knowing what is best for each person cannot be mentioned in a book; rather, it requires guidance from Allah."