What does « Knot / Contract » mean in the Quran?

There is no blame upon you for that to which you [indirectly] allude concerning a proposal to women or for what you conceal within yourselves. Allah knows that you will have them in mind. But do not promise them secretly except for saying a proper saying. And do not determine to undertake a marriage contract until the decreed period reaches its end. And know that Allah knows what is within yourselves, so beware of Him. And know that Allah is Forgiving and Forbearing.

And if you divorce them before you have touched them and you have already specified for them an obligation, then [give] half of what you specified - unless they forego the right or the one in whose hand is the marriage contract foregoes it. And to forego it is nearer to righteousness. And do not forget graciousness between you. Indeed Allah, of whatever you do, is Seeing.

And for all, We have made heirs to what is left by parents and relatives. And to those whom your oaths have bound [to you] - give them their share. Indeed Allah is ever, over all things, a Witness.

O you who have believed, fulfill [all] contracts. Lawful for you are the animals of grazing livestock except for that which is recited to you [in this Qur'an] - hunting not being permitted while you are in the state of ihram. Indeed, Allah ordains what He intends.

Allah will not impose blame upon you for what is meaningless in your oaths, but He will impose blame upon you for [breaking] what you intended of oaths. So its expiation is the feeding of ten needy people from the average of that which you feed your [own] families or clothing them or the freeing of a slave. But whoever cannot find [or afford it] - then a fast of three days [is required]. That is the expiation for oaths when you have sworn. But guard your oaths. Thus does Allah make clear to you His verses that you may be grateful.