An off-duty MTA cleaner’s offhand complaint about a delayed Bronx subway train led to an argument with the repeat offender accused of stabbing him as their quarrel escalated, police sources said Tuesday.

A homeless man with more than 50 prior arrests was charged Sunday with stabbing a man aboard a Lower Manhattan subway train on New Year’s Day, police said. Jamar Banks, 52, who resides in a Brooklyn homeless shelter,

The victim survived being pushed onto the tracks in the attack at the 18th Street station on Tuesday afternoon. A 23-year-old man was charged with attempted murder.