Overall meaning : The desert Arabs who were left behind in the year of Al-Hudaybiyyah, will say, ‘When you set forth with your companions to Khaybar to take the spoils Allah has promised you, Messenger, let us come with you!’
By begging to go forth with you, they seek to change Allah’s promise that only those who were present at Al-Hudaybiyyah and none else would take the spoils of Khaybar. Say to them, Muhammad, ‘You will not join us to fight the Battle of Khaybar. Thus had Allah said to us before returning to you from Al-Hudaybiyyah.’ They will say, ‘You only envy us having a share of the booty.’ The fact of the matter is that they do not understand but a little!
Say to those desert Arabs who stayed behind, Muhammad, ‘You will be called forth to fight against a people who possess immense military might unless they willingly embrace Islam. If you obey this order, Allah will give you a glorious reward; but if you disobey Allah as you did when you preferred staying behind to going forth to Al-Hudaybiyyah, He will inflict on you a grievous punishment.’
Neither the blind, nor the lame, nor the sick will incur any sin if they do not go forth to war alongside the believers by reason of such legitimate excuse preventing them from fighting. Allah will admit those who obey Him and His Messenger into gardens beneath which rivers flow, but on those who turn away from obeying Him and His Messenger He will inflict an agonising punishment.