The word(s) "weak" appears 23 time(s) in 20 verse(s) in Quran in Muhammad Pickthal translation.

(1) O ye who believe! When ye contract a debt for a fixed term, record it in writing. Let a scribe record it in writing between you in (terms of) equity. No scribe should refuse to write as Allah hath taught him, so let him write, and let him who incurreth the debt dictate, and let him observe his duty to Allah his Lord, and diminish naught thereof. But if he who oweth the debt is of low understanding, or weak, or unable himself to dictate, then let the guardian of his interests dictate in (terms of) equity. And call to witness, from among your men, two witnesses. And if two men be not (at hand) then a man and two women, of such as ye approve as witnesses, so that if the one erreth (through forgetfulness) the other will remember. And the witnesses must not refuse when they are summoned. Be not averse to writing down (the contract) whether it be small or great, with (record of) the term thereof. That is more equitable in the sight of Allah and more sure for testimony, and the best way of avoiding doubt between you; save only in the case when it is actual merchandise which ye transfer among yourselves from hand to hand. In that case it is no sin for you if ye write it not. And have witnesses when ye sell one to another, and let no harm be done to scribe or witness. If ye do (harm to them) lo! it is a sin in you. Observe your duty to Allah. Allah is teaching you. And Allah is knower of all things.

(2) And with how many a prophet have there been a number of devoted men who fought (beside him). They quailed not for aught that befell them in the way of Allah, nor did they weaken, nor were they brought low. Allah loveth the steadfast.

(3) And let those fear (in their behaviour toward orphans) who if they left behind them weak offspring would be afraid for them. So let them mind their duty to Allah, and speak justly.

(4) Allah would make the burden light for you, for man was created weak.

(5) Those who believe do battle for the cause of Allah; and those who disbelieve do battle for the cause of idols. So fight the minions of the devil. Lo! the devil's strategy is ever weak.

(6) They consult thee concerning women. Say: Allah giveth you decree concerning them, and the Scripture which hath been recited unto you (giveth decree), concerning female orphans and those unto whom ye give not that which is ordained for them though ye desire to marry them, and (concerning) the weak among children, and that ye should deal justly with orphans. Whatever good ye do, lo! Allah is ever Aware of it.

(7) And when Moses returned unto his people, angry and grieved, he said: Evil is that (course) which ye took after I had left you. Would ye hasten on the judgment of your Lord? And he cast down the tablets, and he seized his brother by the head, dragging him toward him. He said: Son of my mother! Lo! the folk did judge me weak and almost killed me. Oh, make not mine enemies to triumph over me and place me not among the evil-doers.

(8) That (is the case); and (know) that Allah (it is) Who maketh weak the plan of disbelievers.

(9) Now hath Allah lightened your burden, for He knoweth that there is weakness in you. So if there be of you a steadfast hundred they shall overcome two hundred, and if there be of you a thousand (steadfast) they shall overcome two thousand by permission of Allah. Allah is with the steadfast.

(10) Not unto the weak nor unto the sick nor unto those who can find naught to spend is any fault (to be imputed though they stay at home) if they are true to Allah and His messenger. Not unto the good is there any road (of blame). Allah is Forgiving, Merciful.