Al-Baqarah 2:235

وَلَا جُنَاحَ عَلَيۡكُمۡ فِيمَا عَرَّضۡتُم بِهِۦ مِنۡ خِطۡبَةِ ٱلنِّسَآءِ أَوۡ أَكۡنَنتُمۡ فِيٓ أَنفُسِكُمۡۚ عَلِمَ ٱللَّهُ أَنَّكُمۡ سَتَذۡكُرُونَهُنَّ وَلَٰكِن لَّا تُوَاعِدُوهُنَّ سِرًّا إِلَّآ أَن تَقُولُواْ قَوۡلٗا مَّعۡرُوفٗاۚ وَلَا تَعۡزِمُواْ عُقۡدَةَ ٱلنِّكَاحِ حَتَّىٰ يَبۡلُغَ ٱلۡكِتَٰبُ أَجَلَهُۥۚ وَٱعۡلَمُوٓاْ أَنَّ ٱللَّهَ يَعۡلَمُ مَا فِيٓ أَنفُسِكُمۡ فَٱحۡذَرُوهُۚ وَٱعۡلَمُوٓاْ أَنَّ ٱللَّهَ غَفُورٌ حَلِيمٞ 235

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