they demanded ask your lord to describe the kind of cow he wants us to slaughter. moses explained it must be neither too old nor too young thus do whatever you are commanded to do. moses then told them to do as they were ordered.
قالوا ادع لنا ربك يبين لنا ما هي قال إنه يقول إنها بقرة لا فارض ولا بكر عوان بين ذلك فافعلوا ما تؤمرون