Below is the Dua to be recited Between Two Prostrations.
Ibn Abbas narrated:
"Between the two prostrations, the Prophet would say: (Allahummaghfir li, warhamni, wajburni, wahdini, warzuqni).
'O Allah! Pardon me, have mercy on me, help me, guide me, and grant me sustenance.'"
Reference : Jami` at-Tirmidhi 284
In-book reference : Book 2, Hadith 136
English translation : Vol. 1, Book 2, Hadith 284