Short answer
Ask about what will shape your life together: prayer and practice, character and temper, where you will live, work and money, children and how to raise them, family expectations and in-laws, health, and any previous marriage. Islam encourages these talks when they have a purpose, with family involved and without being alone together.
Getting to know a prospective spouse for marriage is permissible and encouraged within the limits of modesty: purposeful talk, no seclusion (khalwah), no touching, and the wali or family aware. A man looking at the woman's face and hands to decide is sunnah.
The four schools agree on this.
Explanation
The Prophet ﷺ said a woman is married for her wealth, family, beauty and religion, and told us to win the one with religion. He also said that when someone whose religion and character you are pleased with proposes, you should accept. So the questions that matter most are about deen and character, then the practical things that make a home work.
Questions worth asking:
- Faith: Do you pray five times a day? What does your week look like as a Muslim? What do you hope to grow in?
- Character: How do you handle anger and disagreement? What would your friends say about you?
- Home: Where do you plan to live? With your parents or separately? See living with in-laws.
- Money: Debts, work, the mahr, and views on interest and spending.
- Work and study: Will either of you work or study after marriage? See a wife working.
- Children: When, how many, and how to raise them.
- Health: Any serious condition that affects married life. See disclosing an illness.
- Past: A previous marriage or children. Past sins that Allah has covered do not need confessing.
Do not rely only on what the person says. Ask people who know them, as the Companions asked the Prophet ﷺ about suitors. Watch for red flags: harshness, control, dishonesty, or a wish to keep your family out.
Keep the talks modest and with a purpose. See talking before nikah. Then pray istikhara and decide. See istikhara for marriage.
The evidence
Quran, Surah Aal-i-Imraan 3:159
فَبِمَا رَحْمَةٍۢ مِّنَ ٱللَّهِ لِنتَ لَهُمْ ۖ وَلَوْ كُنتَ فَظًّا غَلِيظَ ٱلْقَلْبِ لَٱنفَضُّوا۟ مِنْ حَوْلِكَ ۖ فَٱعْفُ عَنْهُمْ وَٱسْتَغْفِرْ لَهُمْ وَشَاوِرْهُمْ فِى ٱلْأَمْرِ ۖ فَإِذَا عَزَمْتَ فَتَوَكَّلْ عَلَى ٱللَّهِ ۚ إِنَّ ٱللَّهَ يُحِبُّ ٱلْمُتَوَكِّلِينَ ﴿١٥٩﴾
So by mercy from Allah, [O Muhammad], you were lenient with them. And if you had been rude [in speech] and harsh in heart, they would have disbanded from about you. So pardon them and ask forgiveness for them and consult them in the matter. And when you have decided, then rely upon Allah. Indeed, Allah loves those who rely [upon Him].
Consult, decide, then put your trust in Allah.
Sahih al-Bukhari 5090
Sahih... تنكح المرأة لأربع لمالها ولحسبها وجمالها ولدينها ...
"A woman is married for four things: her wealth, her family standing, her beauty and her religion."
Religion comes first in choosing a spouse.
Jami' at-Tirmidhi 1084
Grading to be checked... إذا خطب إليكم من ترضون دينه وخلقه فزوجوه ...
"When someone whose religion and character you are pleased with proposes to you, marry him."
Religion and character are what to ask about.
Where the ruling is recorded
- al-Hidaya, Kitab al-Karahiyya, Fasl fi al-Wat' wa al-Nazar wa al-Lams. A man may look at the face and hands of a woman he intends to marry.
- Radd al-Muhtar (Ibn Abidin), Kitab al-Hazr wa al-Ibaha, on looking. The limits of looking and speaking before nikah.
This answer is pending review by the scholars on our team. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.