The sale of a slave (for a slave) and an animal for an animal on credit

وَاشْتَرَى ابْنُ عُمَرَ رَاحِلَةً بِأَرْبَعَةِ أَبْعِرَةٍ مَضْمُونَةٍ عَلَيْهِ، يُوفِيهَا صَاحِبَهَا بِالرَّبَذَةِ. وَقَالَ ابْنُ عَبَّاسٍ قَدْ يَكُونُ الْبَعِيرُ خَيْرًا مِنَ الْبَعِيرَيْنِ. وَاشْتَرَى رَافِعُ بْنُ خَدِيجٍ بَعِيرًا بِبَعِيرَيْنِ فَأَعْطَاهُ أَحَدَهُمَا وَقَالَ آتِيكَ بِالآخَرِ غَدًا رَهْوًا، إِنْ شَاءَ اللَّهُ. وَقَالَ ابْنُ الْمُسَيَّبِ لاَ رِبَا فِي الْحَيَوَانِ الْبَعِيرُ بِالْبَعِيرَيْنِ، وَالشَّاةُ بِالشَّاتَيْنِ إِلَى أَجَلٍ. وَقَالَ ابْنُ سِيرِينَ لاَ بَأْسَ بَعِيرٌ بِبَعِيرَيْنِ نَسِيئَةً.And Ibn ‘Umar bought a mount (riding camel) for four camels which he promised to deliver at Ar-Rabadha. Ibn ‘Abbas said, “One camel may be better than two.” Rafi‘ bin Khadij once bought a camel for two camels and he delivered one instantly and said, “If Allah will, I will bring you the other tomorrow without delay.” And said Ibn Al-Musaiyab, “There is no Riba (in animals) i.e., in selling one camel for two, or one sheep for two sheep on credit.” Ibn Sirin said, “There is no harm in selling one camel for two on credit.”