The word(s) "main" appears 42 time(s) in 40 verse(s) in Quran in Abdullah Yusuf Ali translation.

(11) Lest ye should say: "The Book was sent down to two Peoples before us, and for our part, we remained unacquainted with all that they learned by assiduous study:"

(12) Or think ye that ye shall be abandoned, as though Allah did not know those among you who strive with might and main, and take none for friends and protectors except Allah, His Messenger, and the (community of) Believers? But Allah is well-acquainted with (all) that ye do.

(13) It is not for such as join gods with Allah, to visit or maintain the mosques of Allah while they witness against their own souls to infidelity. The works of such bear no fruit: In Fire shall they dwell.

(14) The mosques of Allah shall be visited and maintained by such as believe in Allah and the Last Day, establish regular prayers, and practise regular charity, and fear none (at all) except Allah. It is they who are expected to be on true guidance.

(15) Do ye make the giving of drink to pilgrims, or the maintenance of the Sacred Mosque, equal to (the pious service of) those who believe in Allah and the Last Day, and strive with might and main in the cause of Allah? They are not comparable in the sight of Allah: and Allah guides not those who do wrong.

(16) Those who believe, and suffer exile and strive with might and main, in Allah's cause, with their goods and their persons, have the highest rank in the sight of Allah: they are the people who will achieve (salvation).

(17) They prefer to be with (the women), who remain behind (at home): their hearts are sealed and so they understand not.

(18) The ground (of complaint) is against such as claim exemption while they are rich. They prefer to stay with the (women) who remain behind: Allah hath sealed their hearts; so they know not (What they miss).

(19) Nor should the Believers all go forth together: if a contingent from every expedition remained behind, they could devote themselves to studies in religion, and admonish the people when they return to them,- that thus they (may learn) to guard themselves (against evil).

(20) Such is Allah, your real Cherisher and Sustainer: apart from truth, what (remains) but error? How then are ye turned away?