Can I make du'a in my own language while in sujood?

Why the scholars allow it

The evidence is the generality of the command itself. The Prophet ﷺ said:

"As for sujood, strive hard in supplication, for it is likely that you will be answered."— Sahih Muslim, from Ibn Abbas

The narration commands ijtihad in du'a — earnest, abundant asking — and attaches no condition of language. Shaykh al-Shanqiti's argument is that this generality is the point: the texts on the merit of du'a are unrestricted, and no text requires the du'a to be in Arabic. He notes that a condition of Arabic does exist, but it applies elsewhere.

Where Arabic is required, and where it is not

The distinction the scholars draw is between two categories:

• Fixed, prescribed formulas — the tashahhud, the takbirs, the tasmiyah, the tahmid, and similar — where the exact wording is specified. These must be in Arabic; substituting another language is not permitted for one who is able.
• Du'a proper — free supplication, where the worshipper asks his Lord for what he needs. Here the wording is not fixed, and the language is not restricted.

Shaykh al-Shanqiti puts it this way:

"The texts are general regarding the legitimacy of du'a... and no condition that the du'a be in Arabic was reported. The condition of Arabic applies only to the specific dhikr: the tashahhud, the takbirs, the tasmiyah, the tahmid and similar things in which the exact wording is required. As for du'a, the correct view among the scholars is that the worshipper may supplicate in his own language and tongue."— Shaykh Muhammad al-Mukhtar al-Shanqiti, Sharh Zad al-Mustaqni'

Not every scholar agreed: some, including scholars of the Hanbali school, disliked supplicating in another language within the prayer for one who is able to do so in Arabic. Outside the prayer there is no such dislike.

The concession for one who cannot manage Arabic

Shaykh al-Shanqiti gives a second, complementary reason: many new Muslims, and non-Arabs generally, cannot learn the Arabic wording except after considerable time and effort. The concession is therefore widened for them. He cites the Prophet's ﷺ words

"then let him choose whatever request he wishes" (Sahih Muslim)

and observes that this was not tied to any particular language. He applies this explicitly to du'a "whether after finishing the tashahhud or while in sujood."

What this means in practice

• You may ask in your own language for whatever you need — forgiveness, health, a righteous spouse, good offspring, relief from hardship.
• The sunnah formulas remain best. Shaykh Ibn Baz notes that the du'a in sujood has no fixed limit, but that supplicating with what is transmitted from the Prophet ﷺ is better. Among these is: "O Allah, forgive me all my sins, the small and the great, the first and the last, the open and the secret" (Sahih Muslim 483).
• Do not recite Qur'an in sujood. The Prophet ﷺ was forbidden to recite Qur'an while bowing or prostrating (Sahih Muslim 479). However, Shaykh Ibn Baz and Shaykh Ibn Uthaymeen both hold that Qur'anic verses containing du'a may be said in sujood with the intention of supplication, not recitation.
• This applies to every sujood — obligatory and voluntary prayer alike, and to the imam, the one praying behind him, and the one praying alone.

Key takeaways

• Du'a in sujood may be made in your own language; the scholars place no condition of Arabic on free supplication.
• The requirement of Arabic applies to the fixed dhikr — tashahhud, takbir, tasmiyah and the like — not to du'a.
• Sujood is among the best places for du'a, so ask abundantly, in whatever words you can manage.
• Supplicating with the formulas transmitted from the Prophet ﷺ is better when you are able, but inability is not a barrier to asking your Lord.
• Do not recite Qur'an in sujood as recitation; Qur'anic du'a said with the intention of supplication is permitted.

Further reading

• Shaykh Muhammad al-Mukhtar al-Shanqiti, Sharh Zad al-Mustaqni'
• Shaykh Ibn Baz, Majmu' al-Fatawa

And Allah knows best.