Sura al-Baqara 2:235

وَلَا جُنَاحَ عَلَيْكُمْ فِيمَا عَرَّضْتُم بِهِۦ مِنْ خِطْبَةِ ٱلنِّسَآءِ أَوْ أَكْنَنتُمْ فِىٓ أَنفُسِكُمْ عَلِمَ ٱللَّـهُ أَنَّكُمْ سَتَذْكُرُونَهُنَّ وَلَٰكِن لَّا تُوَاعِدُوهُنَّ سِرًّا إِلَّآ أَن تَقُولُوا۟ قَوْلًا مَّعْرُوفًا وَلَا تَعْزِمُوا۟ عُقْدَةَ ٱلنِّكَاحِ حَتَّىٰ يَبْلُغَ ٱلْكِتَٰبُ أَجَلَهُۥ وَٱعْلَمُوٓا۟ أَنَّ ٱللَّـهَ يَعْلَمُ مَا فِىٓ أَنفُسِكُمْ فَٱحْذَرُوهُ وَٱعْلَمُوٓا۟ أَنَّ ٱللَّـهَ غَفُورٌ حَلِيمٌ

wa-lā junāḥa ʿalaykum fī-mā ʿarraḍtum bihi min khiṭbati l-nisāʾi aw aknantum fī anfusikum ʿalima allāhu annakum sa-tadhkurūnāhunna wa-lākin lā tuwāʿidūhunna sirran illā an taqūlū qawlan maʿrūfan wa-lā taʿzimū ʿuqdata l-nikāḥi ḥattā yablugha l-kitābu ajalahu waʿlamū annā allāha yaʿlamu mā fī anfusikum faḥdharūhu wa-iʿlamū annā allāha ghafūrun ḥalīmun

There is no blame on you if ye make an offer of betrothal or hold it in your hearts. Allah knows that ye cherish them in your hearts: But do not make a secret contract with them except in terms Honourable, nor resolve on the tie of marriage till the term prescribed is fulfilled. And know that Allah Knoweth what is in your hearts, and take heed of Him; and know that Allah is Oft-forgiving, Most Forbearing.