The final days of Ramadan including the last 10 days {Third Ashra} starts from 21st Ramadan and ends 29th or 30th Ramadan according to the moon. Third Ashra is known as Safety from the Hell. Every Muslim must pray to be safe from Hellfire. The Last Ashra is very important and superior. In this last 10 days the Night of Power (the day ALLAH gave the angels the holy book that then passed on to the Prophet Mohamed “SWT” the Quran), Lailatul Qadar also falls and many Muslims also practice Aitkaf (seclusion for prayers) in this Ashra and try to maximise their prayers.
Stated in Quran:
“We sent it (Quran) down on a blessed Night. Verily,We are ever warning. Therein (in that Night) is decreed every matter of ordainment. Amran (i.e. a command or this Quran or His Decree of every matter) from Us. Verily, We are ever sending (the Messenger) (As) a Mercy from your Lord.” [Quran 44: 3-6]
Dua of third Ashra is:
ﺍﻟﻠﻬﻢ ﺃﺟﺮﻧﺎ ﻣﻦ ﺍﻟﻨﺎﺭ
Translation: “O Allah, save me from the fire of Hell”