مَا حَرْفٌ زَائِدَةٌ

A word in the Arabic language will either be 1) a verb or 2) a noun or 3) a particle – مَا حَرْفٌ زَائِدَةٌ is a particle 

مَا is on occasion used as a supplemental particle

مَعْرِفَةٌمَبْنِيٌّمَا الزَّائِدِDoesحَرْفٌمَا الزَّائِدِ
DefiniteFixedRootمَاParticleSupplemental particle
Surah/Below are the 13 verses in the holy Quran containing the supplemental particleمَا الزَّائِدِ
Verse
Verily Allah is not averse to set forth a parable of a gnatإِنَّ اللهَ لَا يَسْتَحْيِي أَنْ يَضْرِبَ مَثَلًا مَّا بَعُوْضَةً 
or what is more than it and as for the believers they know that it is the truthفَمَا فَوْقَهَا فَأَمَّا الَّذِيْنَ ءَامَنُوْا فَيَعْلَمُوْنَ أَنَّهُ الْحَقُّ
from their Lord however as for those who disbelieve they sayمِنْ رَّبِّهِمْ وَأَمَّا الَّذِيْنَ كَفَرُوْا فَيَقُوْلُوْنَ
“what did Allah SWT mean by this parable?” By it He misleads manyمَاذَا أَرَادَ اللهُ بِهَاذَا مَثَلً يُضِلُ بِهِ كَثِيْرًا
2-26and by it He guides many and He does not mislead by it but the rebelliousوَيَهْدِي بِهِ كَثِيْرًا وَمَا يُضِلُّ بِهِ إِلَّا الْفَاسِقِيْنَ
2-144
2-148
2-150
3-159
4-155
5-13
5-93
7-3
7-10
13-40
As for man, when his Lord tries him by giving him honor and bountiesفَأَمَّا الإِنْسَانُ إِذَا مَا ابْتَلَاهُ رَبُّهُ فَأَكْرَمَهُ وَنَعَّمَهُ
89-15then he says “my Lord has honored me” فَيَقُوْلُ رَبِّي أَكْرَمَنِي
but when He tries him by straitening his means of lifeوَأَمَّا إِذَا مَا ابْتَلَاهُ فَقَدَرَ عَلَيْهِ رِزْقَهُ
89-16he says “my Lord has humiliated me”فَيَقُوْلُ رَبِّي أَهَانَنِ