Nadhr

Nadhr or Nadhir (English: one who warns) is an Arabic word that refers to prophets.إِنَّا أَرْسَلْنَاكَ بِالْحَقِّ بَشِيرًا وَنَذِيرًا وَلاَ تُسْأَلُ عَنْ أَصْحَابِ الْجَحِيمِ"Verily, We have sent thee [Muhammad] with the truth, as a bearer of glad tidings and a warner: and thou shalt not be held accountable for those who are destined for the blazing fire."Qur'an, Chapter 2, verse 119
See more at Wikipedia.org...

Nadhr sing. of "nudhur," one's pledge to do something good, an act of charity, to show appreciation for the Almighty's fulfillment of his/her earnest worldly wish

Solemn vow, pledge.