The Messenger of Allah ﷺ used to say between the two prostrations during the night prayer, "My Lord, forgive me, have mercy on me, mend my state, provide for me, and raise me in rank."
حدثنا أبو كريب محمد بن العلاء حدثنا إسمعيل بن صبيح عن كامل أبي العلاء قال سمعت حبيب بن أبي ثابت يحدث عن سعيد بن جبير
كان رسول الله ﷺ يقول بين السجدتين في صلاة الليل رب اغفر لي وارحمني واجبرني وارزقني وارفعني
[Its chain is daif] Abu Dawud narrated it, in the Book of Prayer, chapter on the supplication between the two prostrations, no. 850, from the hadith of Kamil, with this wording. Tirmidhi considered it gharib, while Hakim and Dhahabi graded it sahih.Habib narrated with "an" (without explicit statement of direct hearing), so see no. 383 regarding his tadlis.