Tafsir of Al-Qasas 28:53

"And when it is recited to them..."

If you ask: What is the difference between the two instances of "indeed" (inna)?

I reply: The first (innahu) is a justification for believing in it, because the fact that it is the truth from God makes it worthy of belief.

The second (inna) is an explanation of His saying: "We believed in it, indeed..." Because that could imply belief that is recent or distant, they were informed that their belief in it is ancient. This is because their ancestors read of its mention in the earlier scriptures, and their descendants after them—"before it" (before its existence and revelation)—were "Muslims," meaning they were upon the religion of Islam; for Islam is the attribute of every monotheist who affirms the revelation.

"Those will be given their reward twice for what they patiently endured, and they repel evil with good, and from what We have provided them, they spend."