كتاب الزكاة
Read the English translation first, with the original Arabic directly underneath.
Narrated Anas:
Abu Bakr wrote to me what Allah had instructed His Messenger (ﷺ) to do regarding the one who had to pay one Bint Makhad (i.e. one year-old she-camel) as Zakat, and he did not have it but had got Bint Labun (two year old she-camel). (He wrote that) it could be accepted from him as Zakat, and the collector of Zakat would return him 20 Dirhams or two sheep; and if the Zakat payer had not a Bint Makhad, but he had Ibn Labun (a two year old he-camel) then it could be accepted as his Zakat, but he would not be paid anything .
وَمَنْ بَلَغَتْ صَدَقَتُهُ بِنْتَ مَخَاضٍ وَلَيْسَتْ عِنْدَهُ وَعِنْدَهُ بِنْتُ لَبُونٍ فَإِنَّهَا تُقْبَلُ مِنْهُ، وَيُعْطِيهِ الْمُصَدِّقُ عِشْرِينَ دِرْهَمًا أَوْ شَاتَيْنِ، فَإِنْ لَمْ يَكُنْ عِنْدَهُ بِنْتُ مَخَاضٍ عَلَى وَجْهِهَا، وَعِنْدَهُ ابْنُ لَبُونٍ فَإِنَّهُ يُقْبَلُ مِنْهُ وَلَيْسَ مَعَهُ شَىْءٌ