We have found three opinions concerning this issue.
1 – That they will be questioned in Syriac.
This was the view of al-Balqeeni, as was narrated from him by his student al-Suyooti in his essay Sharh al-Sudoor fi Ahwaal al-Mawta wa’l-Quboor – but he did not give any reliable evidence for that.
2 – That they will be questioned in Arabic.
This was stated by al-Haafiz Ibn Hajar (may Allaah have mercy on him). Evidence of that may be seen in the apparent meaning of the ahaadeeth, because they describe what will happen in al-Barzakh in Arabic, and there is no reason why this should not be true, and Allaah will inspire everyone who is tested in the grave so that he will understand this language and answer in it.
Ibn Hajar (may Allaah have mercy on him) said:
With regard to the questioning by the two angels, the apparent meaning of the saheeh hadeeth is that it will be in Arabic, because it says that they will say to him: “What do you know about this man?” etc. However it may also be understood as meaning that each person will be addressed in his own language. End quote.
Al-Imtaa’ bi’l-Arba’een al-Mutabaayinatu’l-Samaa’ (p. 122).
3 – That he will be questioned in a language that he understands.
This was mentioned by Ibn Hajar as a possibility, as stated above.
This was also stated in fatwas by the Standing Committee, and by Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on them).
It says in Fataawa al-Lajnah al-Daa’imah (3/450): When a person dies and is buried, two angels come to him and ask him about his Lord, his Prophet and his religion in a language that he understands. End quote.
Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) said:
One of the scholars said: He will be questioned in Syriac. Subhaan-Allaah! Syriac is the language of the Christians. It seems – and Allaah knows best – that this idea was taken from the Christians, so that they could boast and say, Our language is the language of questioning in the grave for everyone who dies.
What appears to be the case is that he will be questioned in whatever language he understands. If he is an Arab then he will be questioned in Arabic and if he is a non-Arab then he will be questioned in his own language. End quote.
Sharh al-‘Aqeedah al-Safaareeniyyah (p. 435), Dar al-Watan.
In our opinion it is better to refrain from commenting on that because there is no saheeh text on this issue, and concerning oneself with these details is something which will not benefit the questioner in either religious or worldly terms. It is sufficient for him to believe that he will be questioned in his grave, and to ask Allaah to help him to obey Him and to inspire him with the right answers, and to make him steadfast when he is questioned.
Shaykh al-Islam Ibn Taymiyah (may Allaah have mercy on him) was asked the following question:
How will the people be addressed on the Day of Resurrection? Will Allaah address them in Arabic? Is it true that the language of the people of Hell will be Farsi and that the language of the people of Paradise will be Arabic?
He (may Allaah have mercy on him) replied:
It is not known which language the people will speak on that Day or in which language they will hear the words of the Lord, may He be glorified and exalted, because Allaah has not told us anything about that, and neither has His Messenger (peace and blessings of Allaah be upon him). It is not true that Farsi is the language of the people of Hell or that Arabic is the language of the people of Paradise. We do not know of any dispute concerning that among the Sahaabah (may Allaah be pleased with them); rather they all refrained from discussing that, because discussing such matters is unnecessary talk. But there was a dispute concerning that among later scholars.
Some people said that they will speak in Arabic, and others said: Except the people of Hell, who will answer in Farsi, which will be their language in Hell. Others said: They will be speak in Syriac, because it is the language of Adam, and from it all other languages stemmed. Others said: Except the people of Paradise, who will speak Arabic.
None of the proponents of these arguments have any evidence, whether based on reason or textual evidence. Rather they are claims that are devoid of any evidence. Allaah knows best and is Most Wise. End quote.
Majmoo’ al-Fataawa (4/300).
And Allaah knows best.