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."  

أَنَّ النَّبِيَّ ﷺ كَانَ يَقُولُ بَيْنَ السَّجْدَتَيْنِ اللَّهُمَّ اغْفِرْ لِي وَارْحَمْنِي وَعَافِنِي وَاهْدِنِي وَارْزُقْنِي