I was the slave (of Abi'l-Lahm). I asked the Messenger of Allah ﷺ if I could give some charity out of my master's wealth. He said: Yes, and the reward is half and half between you two. (Using translation from Muslim 1025a)   

كُنْتُ مَمْلُوكًا فَسَأَلْتُ النَّبِيَّ ﷺ أَتَصَدَّقُ مِنْ مَالِ مَوَالِيَّ بِشَيْءٍ قَالَ نَعَمْ وَالْأَجْرُ بَيْنَكُمَا نِصْفَانِ  

My master commanded me to cut some meat in strips; (as I was doing it) a poor man came to me and I gave him some of it to eat. My master came to know of that, and he beat me. I came to the Messenger of Allah ﷺ and narrated it to him. He (the Holy Prophet) summoned him and said: Why did you beat him? He (Abi'l-Lahm) said: He gives away my food without being commanded to do so. Upon this he (the Holy Prophet) said: The reward would be shared by you two. (Using translation from Muslim 1025b)   

أَنْ أُقَدِّدَ لَحْمًا فَجَاءَنِي مِسْكِينٌ فَأَطْعَمْتُهُ مِنْهُ فَعَلِمَ بِذَلِكَ مَوْلَايَ فَضَرَبَنِي فَأَتَيْتُ رَسُولَ اللهِ ﷺ فَذَكَرْتُ ذَلِكَ لَهُ فَدَعَاهُ فَقَالَ لِمَ ضَرَبْتَهُ؟ فَقَالَ يُعْطِي طَعَامِي بِغَيْرِ أَنْ آمُرَهُ فَقَالَ الْأَجْرُ بَيْنَكُمَا  

[Machine] My lord commanded me to give a dirham every day, so I went to Abu Hurairah and he said, "Fear Allah and fulfill the rights of Allah upon you and the rights of your dependents. For you do not own anything from your wealth or your blood, except that you extend your hand or feed a poor person a morsel." And among those who have been reported that it is permissible for him to donate a small amount of his wealth are Abu Hurairah, Sa'id bin Al-Musayyib, Sa'id bin Jubayr, Al-Hasan Al-Basri, Ash-Sha'bi, An-Nakha'i, Az-Zuhri, and Mak'hul, except that Mak'hul made an exception that he can enjoy it.  

فَرَضَ عَلَيَّ سَيِّدِي كُلَّ يَوْمٍ دِرْهَمًا فَأَتَيْتُ أَبَا هُرَيْرَةَ فَقَالَ اتَّقِ اللهَ وَأَدِّ حَقَّ اللهَ عَلَيْكَ وَحَقَّ مَوَالِيكَ فَإِنَّكَ لَا تَمْلِكُ مِنْ مَالِكَ وَلَا مِنْ دَمِكَ إِلَّا أَنْ تَضَعَ يَدَكَ أَوْ تُطْعِمَ مِسْكِينًا لُقْمَةً وَمِمَّنْ رُوِيَ عَنْهُ أَنَّهُ أَبَاحَ لَهُ أَنْ يَتَصَدَّقَ بِالشَّيْءِ الْيَسِيرِ مِنْ مَالِهِ أَبُو هُرَيْرَةَ وَسَعِيدُ بْنُ الْمُسَيِّبِ وَسَعِيدُ بْنُ جُبَيْرٍ وَالْحَسَنُ الْبَصْرِيُّ وَالشَّعْبِيُّ وَالنَّخَعِيُّ وَالزُّهْرِيُّ وَمَكْحُولٌ إِلَّا أَنَّ مَكْحُولًا عَلَّلَ بِأَنَّهُ يَتَحَلَّلُهُ  

[Machine] Quench his thirst, then inform your family about that.  

فَاسْقِهِ ثُمَّ أَخْبِرْ أَهْلَكَ بِذَلِكَ  

[Machine] "Allah gives an example of a slave who owns nothing and cannot do anything. He does not offer any charity unless he has a herd of cattle to graze. Then a man with a severed throat due to thirst comes to him, fearing that he will die if he is not given water. So, the slave gives him water (7862). Wahb said that Al-Ansari narrated to us, Isma'il narrated to us, Ata narrated from Jabir that he was asked about the slave, does he offer any charity? He said, 'He does not offer any charity.'"  

{ضَرَبَ اللهُ مَثَلًا عَبْدًا مَمْلُوكًا لَا يَقْدِرُ عَلَى شَيْءٍ} [النحل 75] لَا يَتَصَدَّقُ بِشَيْءٍ إِلَّا أَنْ يَكُونَ فِي إِبِلٍ رَاعِيَةٍ فَيَأْتِيَهُ رَجُلٌ قَدِ انْقَطَعَ حَلْقُهُ مِنَ الْعَطَشِ يَخْشَى إِنْ لَمْ يَسْقِهِ أَنْ يَمُوتَ فَإِنَّهُ يَسْقِيهِ 7862 قَالَ وَحَدَّثَنَا الْأَنْصَارِيُّ ثنا إِسْمَاعِيلُ ثنا عَطَاءٌ عَنْ جَابِرٍ أَنَّهُ سُئِلَ عَنِ الْمَمْلُوكِ أَيَتَصَدَّقُ بِشَيْءٍ؟ فَقَالَ لَا يَتَصَدَّقُ بِشَيْءٍ  

[Machine] "To spend from his wealth without giving it to anyone except by the permission of his master, unless he utilizes it for good or clothes oneself. The transmitted hadith indicates that it is possible that the intention of the Prophet ﷺ was to encourage the owner of wealth to allow his slaves to give charity on his behalf, and the reward is between them. And what is apparent from the permissibility is more deserving for the one who desires to follow the Sunnah. And with Allah is the facilitation."  

أَنْ يُنْفِقَ مِنْ مَالِهِ شَيْئًا وَلَا يُعْطِيهِ أَحَدًا إِلَّا بِإِذْنِ سَيِّدِهِ إِلَّا أَنْ يَأْكُلَ فِيهِ بِالْمَعْرُوفِ أَوْ يَكْتَسِيَ وَالْحَدِيثُ الْمُسْنَدُ يَحْتَمِلُ عَلَى الْبُعْدِ أَنْ يَكُونَ قَصَدَ النَّبِيُّ ﷺ تَرْغِيبَ الْمَالِكِ فِي أَنْ يَأْذَنَ لِمَمْلُوكِهِ فِي أَنْ يَتَصَدَّقَ عَنْهُ وَالْأَجْرُ بَيْنَهُمَا وَمَا يَدُلُّ عَلَيْهِ ظَاهِرُهُ مِنَ الْإِبَاحَةِ أَوْلَى بِمَنْ رَغِبَ فِي مُتَابَعَةِ السُّنَّةِ وَبِاللهِ التَّوْفِيقُ