The word(s) "weak" appears 18 time(s) in 16 verse(s) in Quran in Abdullah Yusuf Ali translation.

(11) They will all be marshalled before Allah together: then will the weak say to those who were arrogant, "For us, we but followed you; can ye then avail us to all against the wrath of Allah?" They will reply, "If we had received the Guidance of Allah, we should have given it to you: to us it makes no difference (now) whether we rage, or bear (these torments) with patience: for ourselves there is no way of escape."

(12) We only send the messengers to give Glad Tidings and to give warnings: But the unbelievers dispute with vain argument, in order therewith to weaken the truth, and they treat My Signs as a jest, as also the fact that they are warned!

(13) Say: "If any men go astray, (Allah) Most Gracious extends (the rope) to them, until, when they see the warning of Allah (being fulfilled) - either in punishment or in (the approach of) the Hour,- they will at length realise who is worst in position, and (who) weakest in forces!

(14) It is Allah Who created you in a state of (helpless) weakness, then gave (you) strength after weakness, then, after strength, gave (you weakness and a hoary head: He creates as He wills, and it is He Who has all knowledge and power.

(15) Behold, they will dispute with each other in the Fire! The weak ones (who followed) will say to those who had been arrogant, "We but followed you: Can ye then take (on yourselves) from us some share of the Fire?

(16) At length, when they see (with their own eyes) that which they are promised,- then will they know who it is that is weakest in (his) helper and least important in point of numbers.