All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
The distance for a travelling person to shorten the prayer is 4 Burd, which equals 16 Fursakh. People differed in opinion about estimating this distance in kilometres. Some of them said it equals 88,704 km, while others estimated it approximately to equal 86 km.
4 Burd is equivalent to 48 Hashimite miles, as mentioned by the questioner, but it does not equal 83 miles, by the measurement of today, so we do not know where he got this reference from.