Muwatta Imam Malik Book of Business Transactions, Hadith 73

Yahya related to me from Malik that he had heard that a man said to another, "Buy this camel for me immediately so that I can buy him from you on credit." Abdullah ibn Umar was asked about that and he disapproved of it and forbade it.

وَحَدَّثَنِي عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ أَنَّ رَجُلاً، قَالَ لِرَجُلٍ ابْتَعْ لِي هَذَا الْبَعِيرَ بِنَقْدٍ حَتَّى أَبْتَاعَهُ مِنْكَ إِلَى أَجَلٍ فَسُئِلَ عَنْ ذَلِكَ عَبْدُ اللَّهِ بْنُ عُمَرَ فَكَرِهَهُ وَنَهَى عَنْهُ .