1. Putting your hands on your waist:

It was narrated from Abū Hurayrah (may Allāh be pleased with him) that the Prophet (May Allāh praise him and Peace be upon him) “Prohibited that a man pray with his hands on his waist.” [Reported by Imam Bukhārī: 1220]

2. Raising your gaze towards the sky:

• It was narrated from Abū Hurayrah (may Allāh be pleased with him) that the Prophet (May Allāh praise him and Peace be upon him) said, “People must certainly stop raising their gaze to the sky when they supplicate during prayer, or they will lose their eyesight.” [Reported by Muslim: 429].
• It was narrated from Bakr Ibn ‘Abdillāh that he said “Who is like you, O Son of Ādam! There is nothing between you and the Mihrab! You can enter upon your Lord whenever you wish with no barrier you and Him and no interpreter! There is so much water for you to purify yourself with!” [Ḥilyatu Al Awliyā` 2/229].
• It was narrated from Wakī’ that he said said, “For almost seventy years, Al A’mash caught the opening takbīr (Saying Allāhu Akbar), and some say it was almost sixty years. I never saw him make up a missed rak’ah (unit of prayer).” [Ḥilyatu Al Awliyā` 5/49].
• It was narrated from Sufyān Ibn ‘Uyaynah that he said, “Don’t be like a bad slave who does not come until he is called; come to prayer before the call.” [Ḥilyatu Al Awliyā` 7/285].
• It was narrated from Sufyān Al Thawrī that he would say to a boy when he saw him in the first row, “Have you reached puberty?” If he said “no”, Sufyān would say “Move back.” [Ḥilyatu Al Awliyā` 7/15].
• It was narrated from ‘Alī Ibn Fuḍail that he said, “I saw Sufyān Al Thawrī prostrating at the Kabah and I completed seven laps of tawāf (circumambukation of the Ka’bah) until I saw him lift his head [Ḥilyatu Al Awliyā 7/57].
• It was narrated from Ibn Wahb that he said, “I saw Sufyān Al Thawrī in the Grand Mosque in Mecca after maghrib (sunset) prayer. He prayed then prostrated once and did not raise his head until the called for ‘ishā (night time) prayer was given. [Ḥilyatu Al Awliyā 7/57].
• It was narrated from Yaḥyā Ibn Yūnus that, when Al Ḥasan Ibn Ṣāliḥ was mentioned, he said, “Every prayer time, I would come to the mosque with him and he would lose consciousness when we passed the graveyard.” [Ḥilyatu Al Awliyā` 7/329].
• It was narrated from Ibrāhīm Al Nakha’ī that he said, “If you see a man who is neglectful of catching the first takbīr (Saying Allāhu Akbar), wash your hands of him.” [Ḥilyatu Al Awliyā` 4/215, 232].
• It was narrated from Imrān Ibn Muslim that he said, “Suwaid Ibn Ghaflah mostly said Allāhu Akbar before the muezzin said qad qāmat aṣ ṣalāt (prayer is about to begin).” [Ḥilyatu Al Awliyā 4/175].

3. Looking at something that distracts you or occupies you:

It was narrated from ‘Ā`ishah (may Allāh be pleased with her) that the Prophet (May Allāh praise him and Peace be upon him) prayed while he was wearing a khamīṣa (type of garment with) that had printed marks. He looked at its marks and when he finished prayer, he said, "Take this khamisa of mine to Abū Jahm, for it has distracted me from my prayer, and bring me Abū Jahm’s anbijāniyyah (a plain thick sheet)." [Reported by Bukhārī: 373]

4. Turning towards something when there is no need to do so:

It was narrated from ‘Ā`ishah (may Allāh be pleased with her) that she said, “I asked Allāh’s Messenger (May Allāh praise him and Peace be upon him) about turning towards something during prayer and he said “It is something that Shaytān snatches from a slave’s prayer”” [Reported by Bukhārī: 751].

5. Closing one’s eyes:

Some people do this while praying in an attempt to obtain khushū (submissiveness and humility). However, it is not correct. Sheikh Al Albānī said regarding closing one’s eyes during prayer, “It is makrūh (disliked) and against the Sunnah (Prophetic practice)” [Al Mawsūah Al Fiqhiyyah Al Muyassarah 2/597].

6. Covering the mouth and wearing clothes that reach the ground:

It was narrated from Abū Hurayrah (may Allāh be pleased with him) that Allāh’s Messenger (May Allāh praise him and Peace be upon him) forbade wearing clothes reaching the ground in prayer and that he also forbade men from covering their mouths. [Ṣaḥīḥ Sunan Abī Dāwūd: 597].

7. Speaking during prayer:

It was narrated from ‘Abdullāh Ibn Mas’ūd (may Allāh be pleased with him) that he said, “We have been prohibited from speaking in prayer with the exception of the Qur`ān and dhikr (remembrance)” [Al Silsilah Al Ṣaḥīḥah: 2380]

8. Food being ready or fighting off the two dirty things (the need to urinate or pass stool):

It was narrated from ‘Ā`ishah (may Allāh be pleased with her) that she said that she heard the Prophet (May Allāh praise him and Peace be upon him) say, “You are not to pray if the food is ready or you are fighting off either of the two dirty things.” The two dirty things are urine and stool [Reported by Imam Muslim: 560].

9. Praying when you are drowsy:

It was narrated from ‘Ā`ishah (may Allāh be pleased with her) that the Prophet (May Allāh praise him and Peace be upon him) said, “If you are drowsy/nodding off during prayer, you should sleep until the need for sleep is gone, because if you pray while you are drowsy, you may intend to ask Allāh for forgiveness and end up insulting yourself” [Reported by Bukhārī: 212].

10. Spitting in the direction of the qiblah (prayer direction) or to your right:

The evidence for this is that the Prophet (May Allāh praise him and Peace be upon him) said, “When you pray, Allāh is in front of you, so you must absolutely not spit in His direction or to your right.” [Reported by Imam Muslim: 3008].

11. Yawning:

The evidence for this is that the Prophet (May Allāh praise him and Peace be upon him) said, “ If you yawn while you are praying, repress it as much as you are able to, because Shayṭān will enter” [Reported by Imam Muslim: 2995].

12. Gathering and tucking in one’s hair and garments:

The evidence for this is that the Prophet (May Allāh praise him and Peace be upon him) said, “I was ordered to prostate on seven parts of the body: the forehead (and he pointed at his nose), the hands, the knees and the ends of the feet, and not to tuck in or gather my garments or my hair” [Reported by Imam Al Bukhārī: 490]

13. Putting one’s weight on one’s hand during prayer and interlinking fingers:

It was narrated from Ibn ‘Umar (may Allāh be pleased be with him) that he saw a man put his weight on his left hand while he was sitting in prayer leaning on his left side. So, he said to him, “Do not sit like that, because it is how those who will be punished sit” [Ṣaḥīḥ Sunan Abī Dāwūd: 877].