William Burkitt on Mark 12:38

Observe here, What it is that our Saviour condemns; not civil salutations in the market-place, not the chief seats in synagogues, not the uppermost rooms at feasts; but their fond affecting of these things, and their ambitious aspiring after them. It was not their taking, but their loving, the uppermost rooms a feasts, which Christ condemns.

Observe, 2. How our Saviour condemns the Pharisees for their gross hypocrisy, in covering over their covetousness with a pretence of religion, making long prayers in the temple and synagogues for widows, and thereupon persuading them to give bountifully to corban; that is, the common treasury for the temple, some part of which was employed for their maintenance.

Whence we learn, That it is no new thing for designing hypcocrites to cover the foulest transgressions with the cloke of religion. The Pharisees made long prayers a cloak and cover for their covetousness.