That ye faint not (mē enkakein). Object infinitive with mē after aitoumai. The infinitive (present active) enkakein is a late and rare word (see already Luk 18:1; 2Th 3:13; 2Co 4:1, 2Co 4:16; Gal 6:9) and means to behave badly in, to give in to evil (en, kakos). Paul urges all his apostolic authority to keep the readers from giving in to evil because of his tribulations for them.