And We divided them into twelve tribes , as nations ; and We revealed to Musa when his people asked him for water : Strike the rock with your staff , so outnowed from it twelve springs ; each tribe knew its drinking place ; and We made the clouds to give shade over them and We sent to them manna and quails : Eat of the good things We have given you . And they did not do Us any harm , but they did injustice to their own souls .