Acts that Nullify Salaah
1. If a person speaks in salaah intentionally or unintentionally, his salaah will be nullified.
2. If a person utters the following sounds in salaah, his salaah will be nullified: for example he says: aah, ooh, oof, etc. or he cries out aloud. However, if his heart is overcome by emotion out of thinking of jannah or jahannam and he utters these sounds, then his salaah will not break.
3. By clearing one's throat unnecessarily whereby even half a letter is uttered, salaah will break. However, it is permissible to do this when one is compelled to do so - salaah will not break.
4. A person sneezes in salaah. After sneezing he says Alhamdulillah. His salaah will not break, but it is preferable not to say anything. But if someone else sneezed and this person said Yarhamukallah while he was in salaah, his salaah will break.
5. Continuously looking into the Quran and reading nullifies the salaah. (A glance or two will not break the salaah)
6. Salaah will break if a person turns to such an extent that his chest turns away from the qiblah.
7. If a person replies to someone's salaam by saying Wa alaykumus salaam, his salaah will break.
8. If a woman plaits her hair while offering salaah, her salaah will break.
9. Eating or drinking anything in salaah will break the salaah. So much so that if a person picks up a sesame seed or a small piece of betel leaf, and eats it, his salaah will break. However, if a food particle was stuck in-between his teeth and he swallowed it, his salaah will break if that particle was larger or equal to a gram seed. If it was less than a gram seed, his salaah will not break.
10. If a betel leaf is placed in the mouth and its juice goes down the throat, salaah will break.
11. A person ate something sweet. He then rinsed his mouth and commenced offering his salaah. However, some taste of that sweet thing is still in the mouth and goes down the throat together with his saliva. In this case, his salaah will be in order.
12. While in salaah, a person hears some good news and therefore says Alhamdo lillah. Alternatively, he hears of the death of someone, so he says: Inna lillahi wa inna ilayhi raaji'un. In both cases his salaah will break.
13. A child or something fell down. At the time of its falling the person uttered Bismillah. His salaah will break.
14. While a woman was offering salaah, a child came and drank milk from her. Her salaah will break. However, if the milk did not come out, her salaah will not break.
15. At the time of saying Allahu Akbar, the person lengthened the alif of Allah and said "Aaallah" or Allahu "Aaakbar", or lengthened the baa of Akbar and said "Akbaaar" - in all these cases his salaah will break.
16. While offering salaah, a person's eyes fell on a letter or a book. He did not read it verbally but merely understood its meaning with his heart - his salaah will still be valid. However, if he reads it verbally, his salaah will break.
17. If a person, dog, cat, goat or any other animal walks across the person who is offering salaah, his salaah will not break. But the person who walked across will be committing a sin. One should therefore offer ones salaah at such a place where no one walks in front and people do not have any difficulty in walking about. But if a person cannot find such a secluded spot, he should fix a stick in front of him which is at least one arm's length and equal to a finger in thickness. The person should then stand behind that stick. The stick should not be directly in front of him but should be slightly to the right or left of his eyes. If a person does not fix a stick, he could place anything else which is similar to it, such as a stool. In doing so, it will be permissible to walk across (beyond the stick) and there will be no sin.
18. If, due to some necessity, a person steps slightly forward or backwards without his chest turning away from the qiblah, his salaah will be valid. But if he moves beyond the place of sajdah, his salaah will break.