Sahih Ibn Khuzaymah

Hazrat Musa bin Talha’s respected father narrates from the Noble Prophet (peace be upon him) that he (peace be upon him) said: “Any one of you should place something equal to the rear wooden part of a camel saddle (as a sutrah) in front of him, then things passing in front of him will not harm him.” Imam Abu Bakr (may Allah have mercy on him) says that in the statement of the Prophet (peace be upon him), “When any one of you has something equal to the rear wooden part of a camel saddle in front of him, then things passing in front of him will not harm him,” there is clear evidence that if he does not have a sutrah equal to the rear wooden part of a camel saddle in front of him, then the animals passing in front of him will harm him. And those animals whose passing in front of him is harmful are only those about whom the Noble Prophet (peace be upon him) has stated that they break the prayer, and they are the donkey and the black dog, as Mustafa (peace be upon him) has said. Other animals are not meant, which do not break the prayer.