Maliks Muwatta Book 36, Hadith Number 49.
Section : Judgement on Strays.
Malik related to me from Yahya ibn Said from Sulayman ibn Yasar that Thabit ibn ad-Dahhak al-Ansari told him that he had found a camel at Harra, so he hobbled it and mentioned it to Umar ibn al-Khattab and Umar ordered him to make it known three times. Thabit said to him, “That would distract me from the running of my estate.” Umar said to him, “Then let it go where you found it.”