It is narrated from Sayyiduna Hudhayfah (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) used to say «رب اغفرلي» between the two prostrations. Imam Darimi (may Allah have mercy on him) was asked: Do you also say this? He replied: Sometimes I say it, sometimes I remain silent.
Hadith Referenceسنن دارمي / من كتاب الصللاة / 1361
Hadith Takhrijاس حدیث کی سند میں مقال ہے۔ تفصیل کے لئے دیکھئے: [أبوداؤد 874] ، [نسائي 1068] ، [ابن ماجه 897] ، [أحمد 397/5] ، [شرح السنة للبغوي 910] ، [نيل الأوطار 293/2]
Brief Explanation
(Commentary on Hadith 1360) Saying «اَللّٰهُمَّاغْفِرْلِيْ» or «رَبِّاغْفِرْلِيْ» three times between the two prostrations, or saying «اَللّٰهُمَّاغْفِرْلِيْوَارْحَمْنِيْوَاهْدِنِيْوَعَافِنِىْوَارْزُقْنِيْ», is established from the ahadith. See: [أبوداؤد ، ترمذي و مستدرك الحاكم 262/1].