It is a specific Dhikr performed during the Eid period.
اللَّهُ أَكْبَرُ اللَّهُ أَكْبَرُ، لَا إلَهَ إلَّا اللَّهُ وَاَللَّهُ أَكْبَرُ، اللَّهُ أَكْبَرُ وَلِلَّهِ الْحَمْدُ
Allah is the Greatest, Allah is the Greatest, there is no god except Allah, And Allah is the Greatest, Allah is the Greatest, for Allah is all praise. (Fath al-Qadeer).
The above Dhikr is to be recited after the Fard prayer (Fard Rakahs) for a total of 23 prayers from the day of Arafah, according to the strongest opinion in the Hanafi Madhab. To do so is Waajib, based on the following verse of the Holy Quran.
وَاذْكُرُوا اللَّهَ فِي أَيَّامٍ مَعْدُودَاتٍ
And remember Allah during the appointed days. (Surah al-Baqarah, 203).
وقالا تجب فور كل فرض على من صلاه ولو منفردا أو مسافرا أو قرويا إلى عصر الخامس من يوم عرفة وبه يعمل وعليه الفتوى. (نور الإيضاح)
And they (the Saahibayn) said it is Waajib upon the one who prayed, immediately after the Fard, even if he prayed alone (not in congregation), irrespective of him being a traveller or a village dweller. It is to be performed from the day of Arafah (Fajr) until the Asr prayer of the fifth day (thirteenth Dhul Hijjah), this is acted upon and the Fatwa is on it. (Imam al-Shurunbulali, Nurul Idaah).
There is quite a lot of detail and difference of opinion related to this Masalah, therefore the reader is encouraged to study this subject from a classical book of Fiqh.
And Allah (Most High) knows best.
– Answered by Shaykh Noorud-deen Rashid (09.07.2021)
Increasing Worship in Dhul Hijjah
Cutting Hair and Nails in Dhul Hijjah
Legal Ruling for the Udhiyah (Qurbani)
Reward for Fasting the Day of Arafah
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