What is the ruling of the Shariah regarding the responsibility of a brother towards the children of his deceased brother?

The article summarizes the duties of sponsoring an orphan as: being kind and gentle towards them, and spending on them from the guardian's own money if the orphan has no money, or spending from the orphan's own money if they have it, while preserving and developing their wealth. The article encourages sponsoring an orphan due to its immense reward.