List of awards and nominations received by Slipknot
Grammy Awards

Year
Nominee / work
Award
Result
2001
"Wait and Bleed"
Best Metal Performance
Nominated
2002
"Left Behind"
Best Metal Performance
Nominated
2003
"My Plague"
Best Metal Performance
Nominated
2005
"Duality"
Best Hard Rock Performance
Nominated
2005
"Vermilion"
Best Metal Performance
Nominated
2006
"Before I Forget"
Best Metal Performance
Won
2009
"Psychosocial"
Best Metal Performance
Nominated
2015
"The Negative One"
Best Metal Performance
Nominated
2016
"Custer"
Best Metal Performance
Nominated
2016
.5: The Gray Chapter
Best Rock Album
Nominated

Question: What song did Slipknot receive the Grammy for Best Metal Performance for in 2006? 
Answer: In 2006, "Before I Forget " won a Grammy Award for Best Metal Performance.