Jamieson, Fausset and Brown on 2 Timothy 4:3

3. they--professing Christians.

sound doctrine--Greek, "the sound (see on 1Ti 1:10) doctrine (didascalias)" or "teaching," namely, of the Gospel. Presently follows the concrete, "teachers."

after their own lusts--Instead of regarding the will of God they dislike being interrupted in their lusts by true teachers.

heap--one on another: an indiscriminate mass of false teachers. Variety delights itching ears. "He who despises sound teaching, leaves sound teachers; they seek instructors like themselves" [Bengel]. It is the corruption of the people in the first instance, that creates priestcraft (Ex 32:1).

to themselves--such as will suit their depraved tastes; populus vult decipi, et decipiatur--"the people wish to be deceived, so let them be deceived." "Like priest, like people" (1Ki 12:31; Ho 4:9).

itching--like to hear teachers who give them mere pleasure (Ac 17:19-21), and do not offend by truths grating to their ears. They, as it were, tickle with pleasure the levity of the multitude [Cicero], who come as to a theater to hear what will delight their ears, not to learn [Seneca, Epistles, 10.8] what will do them good. "Itch in the ear is as bad in any other part of the body, and perhaps worse" [South].