[Hence,] O you who have attained to faith, when you go forth [to war] in God's cause, use your discernment, and do not - out of a desire for the fleeting gains of this worldly life - say unto anyone who offers you the greeting of peace, "Thou art not a believer" for with God there are gains abundant. You, too, were once in the same condition - but God has been gracious unto you. Use, therefore, your discernment: verily, God is always aware of what you do.