The word(s) "serve" appears 100 time(s) in 96 verse(s) in Quran in Muhammad Pickthal translation.

(31) We sent Noah (of old) unto his people, and he said: O my people! serve Allah. Ye have no other Allah save Him. Lo! I fear for you the retribution of an Awful Day.

(32) And unto (the tribe of) A'ad (We sent) their brother, Hud. He said: O my people! serve Allah. Ye have no other Allah save Him. Will ye not ward off (evil)?

(33) They said: Hast come unto us that we should serve Allah alone, and forsake what our fathers worshipped? Then bring upon us that wherewith thou threatenest us if thou art of the truthful!

(34) And to (the tribe of) Thamud (We sent) their brother Salih. He said: O my people! serve Allah. Ye have no other Allah save Him. A wonder from your Lord hath come unto you. Lo! this is the camel of Allah, a token unto you; so let her feed in Allah's earth, and touch her not with hurt lest painful torment seize you.

(35) And unto Midian (We sent) their brother, Shu'eyb. He said: O my people! serve Allah. Ye have no other Allah save Him. Lo! a clear proof hath come unto you from your Lord; so give full measure and full weight and wrong not mankind in their goods, and work not confusion in the earth after the fair ordering thereof. That will be better for you, if ye are believers.

(36) And they observe toward a believer neither pact nor honour. These are they who are transgressors.

(37) He only shall tend Allah's sanctuaries who believeth in Allah and the Last Day and observeth proper worship and payeth the poor-due and feareth none save Allah. For such (only) is it possible that they can be of the rightly guided.

(38) O ye who believe! The idolaters only are unclean. So let them not come near the Inviolable Place of Worship after this their year. If ye fear poverty (from the loss of their merchandise) Allah shall preserve you of His bounty if He will. Lo! Allah is Knower, Wise.

(39) (Triumphant) are those who turn repentant (to Allah), those who serve (Him), those who praise (Him), those who fast, those who bow down, those who fall prostrate (in worship), those who enjoin the right and who forbid the wrong and those who keep the limits (ordained) of Allah - And give glad tidings to believers!

(40) (Saying): serve none but Allah. Lo! I am unto you from Him a warner and a bringer of good tidings.