Conflicts in Quran #1

In Enfal Sure at the 65th verse, Allah says

O Prophet! rouse the Believers to the fight. If there are twenty amongst you, patient and persevering, they will vanquish two hundred: if a hundred, they will vanquish a thousand of the Unbelievers: for these are a people without understanding.

But belivers didn't believe the ratio of 1/10. They refuse to go war. Then Allah changes its mind and in the coming verse which is Enfal 66 says;

For the present, Allah hath lightened your (task), for He knoweth that there is a weak spot in you: But (even so), if there are a hundred of you, patient and persevering, they will vanquish two hundred, and if a thousand, they will vanquish two thousand, with the leave of Allah: for Allah is with those who patiently persevere.

1/2 ratio seems more convincing :-)