Sunan Abi Dawud, Hadith 2414

Nafi' said: Ibn 'Umar used to go out to al-Ghabah (jungle), but he neither broke his fast, nor shortened his prayer.

حَدَّثَنَا مُسَدَّدٌ، حَدَّثَنَا الْمُعْتَمِرُ، عَنْ عُبَيْدِ اللَّهِ، عَنْ نَافِعٍ، أَنَّ ابْنَ عُمَرَ، كَانَ يَخْرُجُ إِلَى الْغَابَةِ فَلاَ يُفْطِرُ وَلاَ يَقْصُرُ ‏.‏

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also referenced under: Hadith 2408 (Hasan)