The word(s) "fulfils" appears 3 time(s) in 3 verse(s) in Quran in Mohsin Khan translation.

(1) Yes, whoever fulfils his pledge and fears Allah much; verily, then Allah loves those who are Al-Muttaqun (the pious - See V.2:2).

(2) And be not like her who undoes the thread which she has spun, after it has become strong, by taking your oaths as a means of deception among yourselves, lest a nation should be more numerous than another nation. Allah only tests you by this [i.e who obeys Allah and fulfils Allah's Covenant and who disobeys Allah and breaks Allah's Covenant]. And on the Day of Resurrection, He will certainly make clear to you that wherein you used to differ [i.e. a believer confesses and believes in the Oneness of Allah and in the Prophethood of Prophet Muhammad صلى الله عليه و سلم which the disbeliever denies and that is their difference amongst them in the life of this world] .

(3) Verily, those who give Bai'ah (pledge) to you (O Muhammad صلى الله عليه وسلم) they are giving Bai'ah (pledge) to Allah. The Hand of Allah is over their hands. Then whosoever breaks his pledge, breaks it only to his own harm; and whosoever fulfils what he has covenanted with Allah, He will bestow on him a great reward.