Short answer
The small letters above the lines are waqf (pause) signs added by scholars to help you stop and start where the meaning stays clear. For example, م means you should stop, لا means do not stop, ج means either is fine, صلى means carrying on is better and قلى means stopping is better. Following them is part of good tajweed, not a separate obligation.
The waqf signs are not part of the revealed text; they are aids added by reciters. Missing a sign is not a sin in itself, but deliberately stopping or restarting so as to corrupt the meaning is sinful. In salah, the relied-upon Hanafi fatwa is that a wrong stop or start does not invalidate the prayer, though it should be avoided.
The four schools agree on this.
Explanation
The Quran is to be recited in measured, clear recitation (73:4). Where you take a breath matters: a stop in the wrong place can split a sentence so that it seems to say the opposite of what it means. The scholars of qira'ah marked the best places to pause, and these marks are printed in most copies.
Common signs in the Madinah mushaf:
- م (lazim): stop here. Joining would suggest a wrong meaning.
- لا: do not stop here; if you must, go back and join.
- ج (ja'iz): stopping and continuing are equal.
- صلى: both allowed, continuing is better.
- قلى: both allowed, stopping is better.
- Three dots (∴ ∴): stop at one of the two places, not both.
- The circle with a number: the end of an ayah, where stopping is always fine.
South Asian copies use more letters, such as ط (stop), ز (continuing better), ص (you may stop if out of breath) and سكتة (a short pause without taking a breath). A tajweed teacher can show you the system in your mushaf.
What the rule really is. Ibn al-Jazari, the great teacher of tajweed, wrote that there is no stop in the Quran that is obligatory or forbidden in itself, except where there is a reason: the meaning. So the signs guide you; the sin is in deliberately distorting the sense, for example stopping right after "there is no god" in the shahadah ayah and not continuing.
If you run out of breath in a wrong place, stop, then go back a word or two and continue. See tajweed rules, is tajweed compulsory and mistakes in recitation in salah.
The evidence
Quran, Surah Al-Muzzammil 73:4
أَوْ زِدْ عَلَيْهِ وَرَتِّلِ ٱلْقُرْءَانَ تَرْتِيلًا ﴿٤﴾
Or add to it, and recite the Qur'an with measured recitation.
Recitation should be measured, with pauses in the right places.
Where the ruling is recorded
- al-Muqaddimah al-Jazariyya (Ibn al-Jazari), Section on stopping and starting (al-waqf wa al-ibtida'). States that no stop is obligatory or forbidden in itself except for a reason of meaning.
- Radd al-Muhtar (Ibn Abidin), Kitab al-Salah, chapter on the errors of the reciter (zallat al-qari). Gives the fatwa that a wrong stop or start in salah does not invalidate the prayer, even where it changes the meaning.
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.