Quarterback Johnny Manziel stood up for fellow free agent Colin Kaepernick in a series of tweets Saturday, praising the former San Francisco 49ers quarterback for his charitable work and saying the reasons Kaepernick isn't signed are "non football based."

At the University of San Diego's pro day on Thursday, Manziel threw in front of NFL scouts for the first time since 2015. Scouts from 13 NFL teams were in attendance, drawing questions as to how many teams would attend a Kaepernick workout.

Manziel wants to shut down the Manziel-Kaepernick chatter.

This will probably cause an uproar, but I'm tired of the @Kaepernick7 vs myself comparisons and anger. Kap is doing amazing things right now changing lives and donating millions of dollars. His impact off the field from a societal standpoint is legendary and straight admirable. — Johnny Manziel (@JManziel2) March 24, 2018

Standing up for people who often don't get heard and for a race that continually deals with problem after problem in this country for CENTURIES. This world we live in is absolutely crazy and I believe what he's doing has an amazing impact. — Johnny Manziel (@JManziel2) March 24, 2018

Manziel went on to tout Kaepernick's NFL credentials before wishing him "all the best in your journey."

The facts of the matter are the reason he's not being signed are non football based. The guy took a team to the Super Bowl and continuously wreaked havoc on the NFC West and the league. Maybe he had a bad year two years ago but he's not a bad player and that's a fact.. — Johnny Manziel (@JManziel2) March 24, 2018

In my opinion the guy still has a lot in the tank but it's not my place to say what he wants to do with his career. All I can speak for is myself and trying to turn my life around from the depths it was in. God bless and have a great Saturday... — Johnny Manziel (@JManziel2) March 24, 2018

I rock with you @Kaepernick7 you've always been good to me and I appreciate that. All the best in your journey my friend wherever that takes you — Johnny Manziel (@JManziel2) March 24, 2018

Kaepernick wasn't on an NFL roster last season after he opted out of his 49ers contract before the start of the 2017 league year. He has been reticent to speak out about his playing future or fundraising efforts but said on a few occasions in 2017 that he was still looking for an NFL opportunity.

Video of Kaepernick throwing was posted on Instagram last week.

Manziel has been out of the NFL for two seasons after his release by the Cleveland Browns in March 2016. He has worked out with the CFL's Hamilton Tiger-Cats and is set to play in the Spring League beginning later this month. The 2014 first-round pick has been training with QB guru George Whitfield Jr.

Information from ESPN's Eric D. Williams was used in this report.