Translation
(1) Purification (Kitab Al-Taharah)
كتاب الطهارة
(11) Chapter: Avoiding (The Splatter) Of Urine
(11) باب الاِسْتِبْرَاءِ مِنَ الْبَوْلِ
Sunan Abi Dawud 21 
Narrated Ibn 'Abbas:

A tradition from the Prophet (sal Allaahu alayhi wa sallam ) conveying similar meaning.

The version of Jarir has the wording : "he did not cover himself while urinating."

The version of Abu Mu'awiyah has the wording: "he did not safeguard himself (from urine)."

حَدَّثَنَا عُثْمَانُ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا جَرِيرٌ، عَنْ مَنْصُورٍ، عَنْ مُجَاهِدٍ، عَنِ ابْنِ عَبَّاسٍ، عَنِ النَّبِيِّ صلى الله عليه وسلم بِمَعْنَاهُ قَالَ ‏"‏ كَانَ لاَ يَسْتَتِرُ مِنْ بَوْلِهِ ‏"‏ ‏.‏ وَقَالَ أَبُو مُعَاوِيَةَ ‏"‏ يَسْتَنْزِهُ ‏"‏ ‏.‏
Grade :  Sahih (Al-Albani) صحيح  (الألباني)حكم :
Reference : Sunan Abi Dawud 21
In-book reference : Book 1, Hadith 21
English translation : Book 1, Hadith 21