The sheikh felt when his children and grandchildren did not help him

The answer is: disappointment.

The sheikh was disappointed when his children and grandchildren did not help him. He hoped they could help him somehow and was disappointed when they failed. He was especially disappointed because he had high expectations of his children and grandchildren. Despite his disappointment, the sheikh still believed in the goodness of people and believed that there was some kind of lesson to be learned from this experience. He was determined to maintain a positive outlook and continue to pass on his knowledge and wisdom to the next generation.