Al-Qalam: (46) Or do you ask them a reward...

This verse and those following it have been explained in Surah At-Tur.

I say that the discourse here returns to what preceded it, starting from His statement: {Or do they have partners?} (Al-Qalam: 41).

The meaning of "a burden/fine" (al-ghārim) is a penalty or fine. That is, [the Prophet] did not ask them for a reward for guidance and teaching, which would burden them with the weight of financial penalties, thus discouraging them from faith.