Zamal said, "We must respect the rules of the game." (Make it indirect)

Direct Speech: Zamal said, "We must respect the rules of the game."
Indirect Speech: Zamal said that they had to respect the rules of the game.

• must ↔ had to:
• Direct speech থেকে Indirect speech এ রূপান্তরের বেলায়,
→ Reporting verb এর subject বসে।
→ Reporting verb say/said, tell/told (যদি থাকে) বসে।
→ Inverted comma উঠে that বসে।
→ Direct speech এ must থাকলে Indirect speech এ had to হয়।
→ to এর পর verb এর base form বসবে।
→ বাকি অংশ বসবে।

Source: A Passage to the English Language by S. M. Zakir Hussain.