A 52-page pamphlet has seen a surge in sales in recent days, skyrocketing up the book sales charts on Amazon to the No. 2 spot behind only J.K. Rowling’s “Harry Potter and the Cursed Child,” which was released Sunday.

The sudden bestseller is a pocket version of the U.S. Constitution, which has received attention since Khizr Khan, the father of a Muslim U.S. soldier who was killed by a suicide bomber in Iraq, displayed the book during an emotional attack on Donald Trump at the Democratic National Convention.

The Chicago Tribune reported that the Constitution, which sells for about $1, entered the Top 10 on Saturday afternoon. Fortune notes that the book was in the No. 2 spot on the Amazon list as of Monday afternoon.

Khan, a Muslim-American lawyer, famously addressed Trump during his appearance Thursday at the DNC, holding up his copy of the Constitution and saying: “Have you even read the United States Constitution? I will gladly lend you my copy.”

Since the appearance by Khan and his wife, Ghazala, Trump has drawn criticism for belittling the couple.

Fortune notes that Trump suggested to ABC News’ George Stephanopoulos that Ghazala was not “allowed” to speak, remaining silent during the couple’s appearance at the convention.

“Ghazala Khan responded with a powerful Washington Post op-ed, writing that she chose not to speak at the convention because she was overwhelmed by emotion,” Fortune notes. The report quotes Ghazala Khan writing in the op-ed: “Without saying a thing, all the world, all America, felt my pain. I am a Gold Star mother. Whoever saw me felt me in their heart.”

Here’s a clip of the Khans’ appearance at the convention …