Al-Baqara 2:235

There is no sin on you if you hint a proposal of marriage or keep it concealed in your hearts. Allah knows that you will make mention of them[129], but do not make a secret promise with them, except that you may say something appropriate[130]. Do not resolve a marriage contract until the prescribed time is reached. And know that Allah knows what is in your hearts, so be cautious of Him and know that Allah is All-Forgiving, Most Forbearing.

[129] i.e., the widowed or irrevocably divorced.
[130] e.g. by saying to her, "If one finds a wife like you, he will be happy" or so.

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. Allāh 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[93] reaches its end. And know that Allāh knows what is within yourselves, so beware of Him. And know that Allāh is Forgiving and Forbearing.

[93] The ʿiddah (bereavement period) after the death of a husband.

235. And there is no sin on you if you make a hint of betrothal or conceal it in yourself, Allâh knows that you will remember them, but do not make a promise of contract with them in secret except that you speak an honourable saying according to the Islâmic law.[61] And do not consummate the marriage until the term prescribed is fulfilled. And know that Allâh knows what is in your minds, so fear Him. And know that Allâh is Oft-Forgiving, Most Forbearing.

[61] (V.2:235) e.g. you can say to her, "If one finds a wife like you, he will be happy".

There is no sin for you in that which ye proclaim or hide in your minds concerning your troth with women. Allah knoweth that ye will remember them. But plight not your troth with women except by uttering a recognised form of words. And do not consummate the marriage until (the term) prescribed is run. Know that Allah knoweth what is in your minds, so beware of Him; and know that Allah is Forgiving, Clement.