Short answer
In the Hanafi school the makruh (disliked) acts of salah include looking around, putting your hands on your hips, rolling up or tucking clothes or hair, cracking or interlacing fingers, covering the mouth, praying while needing the toilet or while food you want is served, and men spreading their forearms on the ground in sajdah. The prayer is valid but loses reward.
Makruh acts do not break the prayer. Most of those listed are makruh tahrimi; the Hanafi rule is that a prayer performed with a makruh tahrimi act should be repeated within its time to remove the deficiency. Minor makruh tanzihi acts, such as needless small movements, only reduce reward.
The four schools agree on this.
Explanation
Some things break the prayer, some must be repaired with sajdah sahw, and some only spoil its quality. The Hanafi school calls this last group makruh. When Aisha asked the Prophet ﷺ about looking around in prayer, he said it is a snatch that Shaytan steals from a person's prayer. The main makruh acts in the Hanafi school are:
- Turning the face to look around. Turning the chest from the qibla breaks the prayer.
- Hands on the hips while standing.
- Tucking up or rolling clothes or hair, including praying with a man's hair tied up in a bun; see rolled-up sleeves.
- Cracking or interlacing the fingers.
- Covering the mouth and nose without need; see praying with a mask.
- Letting a shawl hang loose from the head or shoulders without wrapping it (sadl).
- Praying while needing the toilet, or while food you want is served; see praying while needing the toilet.
- Men spreading the forearms flat on the ground in sajdah, or sitting on the heels with knees raised like a dog (iq'a).
- Playing with clothes, beard or phone, and wiping the ground more than once.
- Facing a picture of a living being, or a fire, or a person facing you.
- Yawning without trying to hold it; see yawning in salah.
- Closing the eyes without need (makruh tanzihi); see closing your eyes.
The four schools broadly agree these acts are disliked, though they grade some differently. For what breaks the prayer outright, see what breaks your salah.
The evidence
Quran, Surah Al-Muminoon 23:1-2
بِسْمِ ٱللَّهِ ٱلرَّحْمَٰنِ ٱلرَّحِيمِ قَدْ أَفْلَحَ ٱلْمُؤْمِنُونَ ﴿١﴾ ٱلَّذِينَ هُمْ فِى صَلَاتِهِمْ خَٰشِعُونَ ﴿٢﴾
Certainly will the believers have succeeded: They who are during their prayer humbly submissive
Humble stillness is the aim; these acts work against it.
Sahih al-Bukhari 751
Sahih... هو اختلاس يختلسه الشيطان من صلاة العبد ...
"It is a snatch that Shaytan steals from a servant's prayer."
Looking around in prayer is disliked.
Sahih al-Bukhari 812
Sahih... ولا نكفت الثياب والشعر ...
"And we should not tuck up our clothes or hair."
Tucking up clothes or hair in prayer is disliked.
Sahih Muslim 560
Sahih... لا صلاة بحضرة الطعام ولا وهو يدافعه الأخبثان ...
"There is no prayer when food is served, nor while one is holding back the two needs of the toilet."
Praying while distracted by hunger or the toilet is disliked.
Where the ruling is recorded
- Nur al-Idah with Maraqi al-Falah, Chapter on what is disliked in the prayer. The list of makruh acts of prayer.
- al-Durr al-Mukhtar, Kitab al-Salah, chapter on what invalidates the prayer and what is disliked in it. Every prayer performed with a makruh tahrimi act should be repeated.
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.