Translation
(1) Purification (Kitab Al-Taharah)
كتاب الطهارة
(72) Chapter: Concession In This Regard
(71) باب الرُّخْصَةِ فِي ذَلِكَ
Sunan Abi Dawud 183 
The tradition has also been reported by Qais b. Talq through a different chain of narrators. This version adds the wording:
"during the prayer"
حَدَّثَنَا مُسَدَّدٌ، حَدَّثَنَا مُحَمَّدُ بْنُ جَابِرٍ، عَنْ قَيْسِ بْنِ طَلْقٍ، بِإِسْنَادِهِ وَمَعْنَاهُ وَقَالَ فِي الصَّلاَةِ ‏.‏
Grade :  Sahih (Al-Albani) صحيح  (الألباني)حكم :
Reference : Sunan Abi Dawud 183
In-book reference : Book 1, Hadith 183
English translation : Book 1, Hadith 183