✅ Answer:

عَنْ أَحْمَدَ بْنِ مُحَمَّدٍ عَنِ الْحُسَیْنِ بْنِ سَعِیدٍ عَنْ فَضَالَةَ عَنْ أَبَانٍ عَنْ عَبْدِ الرَّحْمَنِ بْنِ سَیَابَةَ قَالَ قُلْتُ لِأَبِی عَبْدِ اللَّهِ أَدْعُو وَ أَنَا سَاجِدٌ قَالَ نَعَمْ فَادْعُ لِلدُّنْیَا وَ الْآخِرَةِ فَإِنَّهُ رَبُّ الدُّنْیَا وَ الْآخِرَةِ

📚 Al-Kafi, Vol. 3, p. 323

Translation: Abdulrahman ibn Sayabah said: I asked Imam Sadiq (peace be upon him): 'Can I make supplication while in prostration?' He replied: 'Yes, make supplication for both this world and the hereafter, for He is the Lord of both.'

Explanation: Making supplication in prostration is not restricted to the final prostration of the prayer, except for a few cases where specific supplications are mentioned for the last prostration of some voluntary prayers. Therefore, we can choose any of the prostrations for supplication, except for those specific supplications where the Ahlul Bayt have designated a particular place, such as the supplication mentioned for the last prostration of the Maghrib prayer on Friday night.

اللَّهُمَّ فَصَلِّ عَلَی مُحَمَّدٍ وَ آلِ مُحَمَّدٍ وَ عَجِّلْ لِوَلِیِّکَ الْفَرَجَ وَ الْعَافِیَةَ وَ النَّصْرَ