Observe, that at first Satan did not enter into Judas, but only put it into his heart to betray his Master. But after the bread, he entered into him. Wherefore let us beware, that Satan thrust not any of his flaming darts into our heart; for if he do, he then watches till he gets an entrance there himself.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: t. xxxii. 14.