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

(21) When ye have performed the act of worship, remember Allah, standing, sitting and reclining. And when ye are in safety, observe proper worship. Worship at fixed times hath been enjoined on the believers.

(22) They ask thee (O Muhammad) what is made lawful for them. Say: (all) good things are made lawful for you. And those beasts and birds of prey which ye have trained as hounds are trained, ye teach them that which Allah taught you; so eat of that which they catch for you and mention Allah's name upon it, and observe your duty to Allah. Lo! Allah is swift to take account.

(23) O ye who believe! Be steadfast witnesses for Allah in equity, and let not hatred of any people seduce you that ye deal not justly. Deal justly, that is nearer to your duty. Observe your duty to Allah. Lo! Allah is Informed of what ye do.

(24) Lo! We did reveal the Torah, wherein is guidance and a light, by which the prophets who surrendered (unto Allah) judged the Jews, and the rabbis and the priests (judged) by such of Allah's Scripture as they were bidden to observe, and thereunto were they witnesses. So fear not mankind, but fear Me. And My revelations for a little gain. Whoso judgeth not by that which Allah hath revealed: such are disbelievers.

(25) Shall I tell thee of a worse (case) than theirs for retribution with Allah? (Worse is the case of him) whom Allah hath cursed, him on whom His wrath hath fallen and of whose sort Allah hath turned some to apes and swine, and who serveth idols. Such are in worse plight and further astray from the plain road.

(26) If they had observed the Torah and the Gospel and that which was revealed unto them from their Lord, they would surely have been nourished from above them and from beneath their feet. Among them there are people who are moderate, but many of them are of evil conduct.

(27) Say O People of the Scripture! Ye have naught (of guidance) till ye observe the Torah and the Gospel and that which was revealed unto you from your Lord. That which is revealed unto thee (Muhammad) from thy Lord is certain to increase the contumacy and disbelief of many of them. But grieve not for the disbelieving folk.

(28) Say: serve ye in place of Allah that which possesseth for you neither hurt nor use? Allah it is Who is the Hearer, the Knower.

(29) When the disciples said: O Jesus, son of Mary! Is thy Lord able to send down for us a table spread with food from heaven? He said: Observe your duty to Allah, if ye are true believers.

(30) And they say: That which is in the bellies of such cattle is reserved for our males and is forbidden to our wives; but if it be born dead, then they (all) may be partakers thereof. He will reward them for their attribution (of such ordinances unto Him). Lo, He is Wise, Aware.