The Prophet ﷺ used to say between the two prostrations: "O Allah, forgive me, have mercy on me, guide me, heal me, and provide for me." (Using translation from Abū Dāʾūd 850)
أَنَّ النَّبِيَّ ﷺ كَانَ يَقُولُ بَيْنَ السَّجْدَتَيْنِ «اللَّهُمَّ اغْفِرْ لِي وَارْحَمْنِي وَاهْدِنِي وَعَافِنِي وَارْزُقْنِي»