Sahih al-Bukhari 2239b
Sahih al-Bukhari · Book 35: Sales in which a Price is paid for Goods to be Delivered Later (As-Salam) · As-Salam by a definite known specified measure
Narrated Ibn Abi Najih:
حَدَّثَنَا مُحَمَّدٌ، أَخْبَرَنَا إِسْمَاعِيلُ، عَنِ ابْنِ أَبِي نَجِيحٍ، بِهَذَا " فِي كَيْلٍ مَعْلُومٍ وَوَزْنٍ مَعْلُومٍ " .
as above, mentioning only specific measure.