The word(s) "thread" appears 5 time(s) in 4 verse(s) in Quran in Mohsin Khan translation.

(1) It is made lawful for you to have sexual relations with your wives on the night of As-Saum (the fasts). They are Libas [i.e. body cover, or screen, or Sakan, (i.e. you enjoy the pleasure of living with them - as in Verse 7:189) Tafsir At-Tabari ], for you and you are the same for them. Allah knows that you used to deceive yourselves, so He turned to you (accepted your repentance) and forgave you. So now have sexual relations with them and seek that which Allah has ordained for you (offspring), and eat and drink until the white thread (light) of dawn appears to you distinct from the black thread (darkness of night), then complete your Saum (fast) till the nightfall. And do not have sexual relations with them (your wives) while you are in I'tikaf (i.e. confining oneself in a mosque for prayers and invocations leaving the worldly activities) in the mosques. These are the limits (set) by Allah, so approach them not. Thus does Allah make clear His Ayat (proofs, evidence, lessons, signs, revelations, verses, laws, legal and illegal things, Allah's set limits, orders) to mankind that they may become Al-Muttaqun (the pious - See V.2:2).

(2) Have you not seen those (Jews and Christians) who claim sanctity for themselves. Nay, but Allah sanctifies whom He wills, and they will not be dealt with injustice even equal to the extent of a scalish thread in the long slit of a date-stone.

(3) Have you not seen those who were told to hold back their hands (from fighting) and perform As-Salat (Iqamat-as-Salat), and give Zakat but when the fighting was ordained for them, behold! a section of them fear men as they fear Allah or even more. They say: "Our Lord! Why have you ordained for us fighting? Would that You had granted us respite for a short period?" Say: "Short is the enjoyment of this world. The Hereafter is (far) better for him who fears Allah, and you shall not be dealt with unjustly even equal to a scalish thread in the long slit of a date-stone.

(4) And be not like her who undoes the thread which she has spun, after it has become strong, by taking your oaths as a means of deception among yourselves, lest a nation should be more numerous than another nation. Allah only tests you by this [i.e who obeys Allah and fulfils Allah's Covenant and who disobeys Allah and breaks Allah's Covenant]. And on the Day of Resurrection, He will certainly make clear to you that wherein you used to differ [i.e. a believer confesses and believes in the Oneness of Allah and in the Prophethood of Prophet Muhammad صلى الله عليه و سلم which the disbeliever denies and that is their difference amongst them in the life of this world] .