Q: Why do we read Takbeer of Tashreeq? I know it is Waajib but what is the reasoning behind it?
A: The Fuqaha have mentioned that when Jibril (Alayhis Salaam) descended with the ram at the time when Hazrat Ibrahim (Alayhis Salaam) was attempting to slaughter Hazrat Ismail (Alayhis Salaam), he recited Allahu Akbar, Allahu Akbar to stop Hazrat Ibrahim (Alayhis Salaam) from slaughtering. When Hazrat Ibrahim (Alayhis Salaam) saw Hazrat Jibril (Alayhis Salaam) descending he recited La Ilaha Illahu Wallahu Akbar and Hazrat Ismail (layhis Salaam) saw this he recited Allahu Akbar Wa Lillahil Hamd. However, the Muhadditheen have disputed the authenticity of this. The wording of the Takbeer has been mentioned in Musannaf ibn Abi Shaybah with a sound chain of narrators that Hazrat Abdullah ibn Masood (Radiyallahu Anhu) used to recite this and this became the general practice of the Sahabah (Radiyallahu Anhum) (Raddul Muhtar Vol.2 Pg.178)
It is narrated about Hazrat Ali (Radiyallahu Anhu) that he used to recite the Takbeer from after Salatul Fajr (9th Zul Hijjah) on the Day Arafah till Asr of the last day of Tashreeq (13th Zul Hijjah). He used to recite the Takbeer after Asr. (I’laaus Sunan Vol.8 Pg.120 from Musannaf ibn Abi Shaybah and Nasbur Rayah)
Ubaid ibn Umair narrates, “Hazrat Umar ibnul Khattab (Radiyallahu Anhu) used to recite the Takbeer after Fajr on the Day of Arafah (9th Zul Hijjah) till Zuhr of the last day of Tashreeq (13th Zul Hijjah). (I’laaus Sunan Vol.8 Pg.126 from, Hakim)
It is narrated about Hazrat Abdullah ibn Abbas (Radiyallahu Anhuma) that he used to recite the Takbeer from the morning of Arafah (9th Zul Hijjah) till Saltul Asr of the last day of Tashreeq (13th Zul Hijjah). (I’laaus Sunan Vol.8 Pg.126 from Hakim)
Umair ibn Saeed narrates, “Hazrat ibn Masood (Radiyallahu Anhu) came to us. He used to recite the Takbeer from Fajr Salah of the Day of Arafah (9th Zul Hijjah) till Asr on the last day of Tashreeq (13th Zul Hijjah).” (I’laaus Sunan Vol.8 Pg.126 from Hakim)
It is narrated that that Hazrat Abullah ibn Masood (Radiyallahu Anhu) used to recite the following Takbeer in the days of Tashreeq:
اَللهُ أَكْبَر اللهُ أكْبَر، لَا إِلَهَ اِلَّا اللهُ اللهُ أكْبَر، اَللهُ أَكْبَر وَلِلَّهِ الْحَمْد
(I’laaus Sunan Vol.8 Pg.127 from Musannaf ibn Abi Shaybah and Nasbu Rayah)
And Allah Ta’ala Knows Best