The word(s) "gain" appears 419 time(s) in 395 verse(s) in Quran in Muhammad Habib Shakir translation.

(41) Let not the believers take the unbelievers for friends rather than believers; and whoever does this, he shall have nothing of (the guardianship of) Allah, but you should guard yourselves against them, guarding carefully; and Allah makes you cautious of (retribution from) Himself; and to Allah is the eventual coming.

(42) And among the followers of the Book there are some such that if you entrust one (of them) with a heap of wealth, he shall pay it back to you; and among them there are some such that if you entrust one (of them) with a dinar he shall not pay it back to you except so long as you remain firm in demanding it; this is because they say: There is not upon us in the matter of the unlearned people any way (to reproach); and they tell a lie against Allah while they know.

(43) Yea, whoever fulfills his promise and guards (against evil)-- then surely Allah loves those who guard (against evil).

(44) Most surely there is a party amongst those who distort the Book with their tongue that you may consider it to be (a part) of the Book, and they say, It is from Allah, while it is not from Allah, and they tell a lie against Allah whilst they know.

(45) Then whoever fabricates a lie against Allah after this, these it is that are the unjust.

(46) And whatever good they do, they shall not be denied it, and Allah knows those who guard (against evil).

(47) (As for) those who disbelieve, surely neither their wealth nor their children shall avail them in the least against Allah; and these are the inmates of the fire; therein they shall abide.

(48) Lo! you are they who will love them while they do not love you, and you believe in the Book (in) the whole of it; and when they meet you they say: We believe, and when they are alone, they bite the ends of their fingers in rage against you. Say: Die in your rage; surely Allah knows what is in the breasts.

(49) And guard yourselves against the fire which has been prepared for the unbelievers.

(50) And hasten to forgiveness from your Lord; and a Garden, the extensiveness of which is (as) the heavens and the earth, it is prepared for those who guard (against evil).