❖ Question:
Is the commonly recited duʿā’ between two sajdahs —
"اللهم اغفر لي، وارحمني، واهدني، وعافني، وارزقني"
— an authentic ḥadīth or weak? And if weak, which duʿā’ should be recited instead?
Answer:
الحمد لله، والصلاة والسلام علىٰ رسول الله، أما بعد!
➊ Status of the Duʿā’:
"اللهم اغفر لي، وارحمني، واهدني، وعافني، وارزقني"
This narration contains a weak chain, due to the presence of Ḥabīb ibn Abī Thābit, a mudallis (narrator known for concealed transmission).
➋ Supporting Hadith in Ṣaḥīḥ Muslim:
Despite its weak sanad, the exact words of this duʿā’ are authentically recorded in:

The Prophet ﷺ taught a new Muslim these exact words in the context of prayer, which grants this duʿā’ validity as a general supplication within ṣalāh.

➌ Most Authentic Duʿā’ Between Two Sajdahs:
The most sound and unanimously accepted duʿā’ for this position is:
"رَبِّ اغْفِرْ لِي، رَبِّ اغْفِرْ لِي"



Conclusion:
❖ The longer duʿā’:
"اللهم اغفر لي، وارحمني، واهدني، وعافني، وارزقني"
— is ḥasan due to corroborating evidence in Ṣaḥīḥ Muslim.
It is permissible and rewardable to recite.
❖ The shorter duʿā’:
"رَبِّ اغْفِرْ لِي، رَبِّ اغْفِرْ لِي"
— is authentically established and remains the safest and best practice in line with the sunnah.
ھٰذَا مَا عِندِي، وَاللّٰهُ أَعْلَمُ بِالصَّوَاب