"And when you left your family," meaning: on the day of Uhud, "to set up" - that is: to assign - "the believers in stations for battle."
﴿وَإِذ غَدَوْت من أهلك﴾ يَعْنِي: يَوْم أحد ﴿تبوئ﴾ أَي: تنزل ﴿الْمُؤْمِنِينَ مَقَاعِدَ لِلْقِتَالِ﴾
