Amir al-Sha'bi (may Allah have mercy on him) reported that the Messenger of Allah (peace and blessings be upon him) said: "Whoever finds an animal whose owners had become unable to feed it, so they let it go, and then someone takes it and revives it (restores it to health), it belongs to him (the one who cared for it)." Ubaydullah said: I asked: From whom is this hadith reported? He (al-Sha'bi) said: It is reported from several of the noble Companions (may Allah be pleased with them).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب اللقطة / 12113
Al-Sha'bi (may Allah have mercy on him) narrates from the Prophet (peace and blessings be upon him) in marfu' form that he (peace and blessings be upon him) said: "Whoever leaves an animal in a place of destruction, and then a man revives it, it belongs to the one who revived it."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب اللقطة / 12114
Ubaydullah bin Humayd (may Allah have mercy on him) said: I heard Imam al-Sha'bi (may Allah have mercy on him) say: Whoever abandons his animal because of sickness, it belongs to the one who treated it and restored it to health. Ubaydullah (may Allah have mercy on him) said: I said: O Abu Amr! From whom is this reported? He said: If you wish, I will count them out for you from the Companions of the Messenger of Allah (peace and blessings be upon him).
There is disagreement over whether this hadith is marfu' (attributed to the Prophet), and as a report from the Prophet (peace and blessings be upon him) it is munqati' (its chain is broken).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب اللقطة / 12115
It is reported from Imam al-Sha'bi (may Allah have mercy on him) regarding a man who lets his animal go, and then another man takes it and restores it: al-Sha'bi (may Allah have mercy on him) said: "This has already been ruled upon: if he let it go in a place of pasture, water and safety, its original owner has more right to it; and if he let it go in a desert and a place of danger, the one who took it has more right to it."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب اللقطة / 12116