The word(s) "strengthen" appears 20 time(s) in 19 verse(s) in Quran in Muhammad Habib Shakir translation.

(11) And We strengthened their hearts with patience, when they stood up and said: Our Lord is the Lord of the heavens and the earth; we will by no means call upon any god besides Him, for then indeed we should have said an extravagant thing.

(12) strengthen my back by him,

(13) And those who disbelieve say: Why has not the Quran been revealed to him all at once? Thus, that We may strengthen your heart by it and We have arranged it well in arranging.

(14) And the heart of Musa's mother was free (from anxiety) she would have almost disclosed it had We not strengthened her heart so that she might be of the believers.

(15) He said: We will strengthen your arm with your brother, and We will give you both an authority, so that they shall not reach you; (go) with Our signs; you two and those who follow you shall be uppermost.

(16) When We sent to them two, they rejected both of them, then We strengthened (them) with a third, so they said: Surely we are apostles to you.

(17) And We strengthened his kingdom and We gave him wisdom and a clear judgment.

(18) Muhammad is the Apostle of Allah, and those with him are firm of heart against the unbelievers, compassionate among themselves; you will see them bowing down, prostrating themselves, seeking grace from Allah and pleasure; their marks are in their faces because of the effect of prostration; that is their description in the Taurat and their description in the Injeel; like as seed-produce that puts forth its sprout, then strengthens it, so it becomes stout and stands firmly on its stem, delighting the sowers that He may enrage the unbelievers on account of them; Allah has promised those among them who believe and do good, forgiveness and a great reward.

(19) You shall not find a people who believe in Allah and the latter day befriending those who act in opposition to Allah and His Apostle, even though they were their (own) fathers, or their sons, or their brothers, or their kinsfolk; these are they into whose hearts He has impressed faith, and whom He has strengthened with an inspiration from Him: and He will cause them to enter gardens beneath which rivers flow, abiding therein; Allah is well-pleased with them and they are well-pleased with Him these are Allah's party: now surely the party of Allah are the successful ones.