Short answer
No. A man's head is not part of his awrah, so covering it is not fard or wajib, and his prayer is valid bareheaded. In the Hanafi school wearing a cap or turban for prayer is good adab, and praying bareheaded out of laziness is makruh tanzihi. Doing so out of humility is not disliked. The four schools agree it is not required.
Praying bareheaded is makruh tanzihi when it comes from laziness or carelessness, and not makruh when done deliberately out of humility. Wearing a topi, kufi or turban is recommended as part of taking one's adornment to the masjid, following the practice of the righteous.
The four schools agree on this.
Explanation
Allah says: take your adornment at every masjid. Scholars explain this as wearing clean, decent and complete clothing for prayer, the clothes you would wear to meet respected people. The Prophet ﷺ and his Companions usually wore head coverings, such as turbans and caps, and many Muslim cultures have kept that habit for prayer.
The ruling for men:
- Not required: the awrah of a man in prayer is from the navel to below the knees. The head is outside it, so the prayer is valid without a cap.
- Better to cover it: in the Hanafi school this is part of the adab of prayer.
- Bareheaded out of laziness: makruh tanzihi, a mild dislike.
- Bareheaded out of humility: some scholars allowed it as a sign of humbleness before Allah.
- Out of contempt for the prayer: that attitude itself is the problem, not the bare head.
Practical points: masjids often keep caps by the door. A cap that covers the forehead must be pushed up so the forehead touches the ground in sajdah. Do not argue with others over caps or make it a mark of who is religious; it is a sunnah of good manners, not a pillar.
Women must cover their hair in prayer, since it is part of their awrah; see do you need hijab to pray at home. For the men's awrah, see awrah for men and women and can you pray in shorts.
The evidence
Quran, Surah Al-A'raaf 7:31
۞ يَٰبَنِىٓ ءَادَمَ خُذُوا۟ زِينَتَكُمْ عِندَ كُلِّ مَسْجِدٍۢ وَكُلُوا۟ وَٱشْرَبُوا۟ وَلَا تُسْرِفُوٓا۟ ۚ إِنَّهُۥ لَا يُحِبُّ ٱلْمُسْرِفِينَ ﴿٣١﴾
O children of Adam, take your adornment at every masjid, and eat and drink, but be not excessive. Indeed, He likes not those who commit excess.
Dressing well for prayer is commanded; a head covering is part of good adornment for many scholars.
Where the ruling is recorded
- al-Durr al-Mukhtar, Kitab al-Salah, chapter on what is disliked in the prayer. Praying bareheaded out of laziness is disliked; out of humility it is not.
- Radd al-Muhtar (Ibn Abidin), Kitab al-Salah, chapter on what is disliked in the prayer. The levels of dislike for praying bareheaded, by intention.
Checked by our team. For a more accurate answer to your own situation, consult a scholar. 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.