No, there is not something specific you have to recite at Sehri time. Rather you must make an intention to fast. Such an intention does not have to be verbalised it can be in your heart.
عَلْقَمَةَ بْنَ وَقَّاصٍ اللَّيْثِيَّ، يَقُولُ: سَمِعْتُ عُمَرَ بْنَ الخَطَّابِ رَضِيَ اللَّهُ عَنْهُ عَلَى المِنْبَرِ قَالَ: سَمِعْتُ رَسُولَ اللَّهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ يَقُولُ: إِنَّمَا الأَعْمَالُ بِالنِّيَّاتِ، وَإِنَّمَا لِكُلِّ امْرِئٍ مَا نَوَى، فَمَنْ كَانَتْ هِجْرَتُهُ إِلَى دُنْيَا يُصِيبُهَا، أَوْ إِلَى امْرَأَةٍ يَنْكِحُهَا، فَهِجْرَتُهُ إِلَى مَا هَاجَرَ إِلَيْهِ
Alqamah bin Waqqas al-Laythi said, he heard Umar bin al-Khattab (May Allah Most High be pleased with him) whilst he was upon the pulpit saying, I heard Allah’s Messenger ﷺ saying, ‘Actions are but by intentions, and each person will have but that which he intended. Thus, he whose emigration was to achieve some worldly gain or to marry a woman, his emigration was for that for which he emigrated.’ (Sahih al-Bukhari, 1).
The noble Hadith above makes it clear that intentions are required when engaging in actions. This point is agreed upon. However, the Sharia does not usually prescribe the exact wording of the intention. In the Hanafi Madhab it is not a requirement to verbalise the intention. Some people believe that there is a specific intention that one must recite in Arabic:
وبصوم غد نَوَيْت مِنْ شهر رمضان
There is no requirement to recite the above intention when beginning ones fast. Rather it seems counter intuitive. If you need to make an intention, why would you do it in a language you do not understand? Therefore, one should make intention in a language he is familiar with. There is no requirement to verbalise the intention, but it is permitted to do so.
قَالَ بَعْضُ الْحُفَّاظِ: لَمْ يَثْبُتْ عَنْ رَسُولِ اللَّهِ – صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ – بِطَرِيقٍ صَحِيحٍ وَلَا ضَعِيفٍ أَنَّهُ كَانَ يَقُولُ عِنْدَ الِافْتِتَاحِ أُصَلِّي كَذَا، وَلَا عَنْ أَحَدٍ مِنْ الصَّحَابَةِ وَالتَّابِعِينَ، بَلْ الْمَنْقُولُ أَنَّهُ كَانَ – صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ – إذَا قَامَ إلَى الصَّلَاةِ كَبَّرَ. (فتح القدير)
One of the Hufaadh (masters of Hadith) said, it is not established, neither in a strong Hadith nor a weak Hadith, that the Prophet ﷺ would say at the beginning of the prayer, ‘I am praying such and such. Nor (is it established) from the Sahabah or Tabieen. Rather what is narrated is he ﷺ would stand for prayer and make the Takbeer (opening glorification).
Similar statements are found in numerous works of the Hanafi Madhab (see Mirqaat al-Mafateeh, Maraaqi al-Falah, al-Bahr al-Raqi, al-Nahr al-Faiq, Radd al-Muhtaar). The Hanafi scholars also mentioned the permissibility of verbalizing the Niyah (intention). However, they clarified that it is not required. This ruling is not limited to fasting or Salah, rather it extends to other acts of worship too.
And Allah Most High Knows Best.
-Answered by Shaykh Noorud-deen Rashid (21.04.2022)
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