What is the ruling on an Imam offering a specific share of captured goods as an incentive after conquering a village?

Primary text

If the Imam grants a specific portion of spoils, such as one garment for every ten garments brought in, or one head of livestock for every ten heads brought in, if people are prevented from collecting them due to lethargy or fear of the enemy, the arrangement is permissible, provided it does not exceed the stipulated legal share. The Imam stating, 'Whoever brings ten garments shall have one garment,' is hoped to incur no issue.