**Question 1:** Who is the Hamas leader that expressed gratitude to Hezbollah's leader?
**Answer:** The Hamas leader who expressed gratitude is Yahya Sinwar.
**Question 2:** What did Yahya Sinwar thank Hassan Nasrallah for?
**Answer:** Yahya Sinwar thanked Hassan Nasrallah for his support in the ongoing war with Israel.
**Question 3:** Which two groups are involved in the conflict mentioned in the article?
**Answer:** The two groups involved in the conflict are Hamas and Hezbollah.
**Question 4:** What is the context of the gratitude expressed by Yahya Sinwar?
**Answer:** The gratitude is expressed in the context of the ongoing war between Hamas and Israel.
**Question 5:** What is the significance of the relationship between Hamas and Hezbollah in this conflict?
**Answer:** The relationship is significant as it indicates collaboration and support between the two groups in their efforts against Israel.