It is 'wajib' (compulsory) to recite 'Takbeeraat-e-Tashreeq' after every 'farz' (obligatory) prayer during the days of 'Tashreeq', beginning from the Fajr prayer on the 9th of Dhul Hijjah until the 'Asr' prayer on the 13th.
It is 'wajib' for men to recite the Takbeeraat aloud and for women to recite them quietly once after each 'farz' prayer.
This ruling applies to prayers performed on time as well as 'qaza' (make-up) prayers during these days.
Additionally, it is obligatory for men to recite the 'Takbeeraat' regardless of whether they perform the prayer in congregation or individually.
The Takbeeraat-e-Tashreeq are as follows:
ٱللَّهُ أَكْبَرُ، ٱللَّهُ أَكْبَرُ، لَا إِلَٰهَ إِلَّا ٱللَّهُ وَٱللَّهُ أَكْبَرُ. ٱللَّهُ أَكْبَرُ، وَلِلَّهِ ٱلْحَمْدُ
(Al-Mu’jam ul-Kabeer lil-Tabaraani, Hadith no. 9538)
Issued by Darul Ifta Al-Ikhlas, Karachi.