Dallas Cowboys defensive end Randy Gregory was conditionally reinstated by the NFL on Friday, and he thanked the league on social media for giving him a "second chance."

Gregory can report to the team on Monday for COVID-19 testing and may participate in conditioning activities, individual workouts and meetings, sources told ESPN's Ed Werder. He may begin practicing with the team the week of Oct. 5, and he will be eligible to participate in games following the team's Week 6 game on Oct. 19.

"Today is a day of celebration and thanks," Gregory posted on Twitter. "... It's go time. I am in a good place and plan to use this second chance to be a great father, player, citizen of Dallas, and teammate. Let's get this!!! #RG94"

Gregory also thanked, among others, NFL commissioner Roger Goodell, Cowboys owner Jerry Jones and NFLPA executive director DeMaurice Smith.

The Cowboys have to cut the roster to 53 players by Saturday, but it is likely they will receive some kind of exemption so that Gregory does not count against the final roster.

Gregory was on an indefinite suspension for multiple violations of the league's substance-abuse policy dating to his rookie year in 2015.

He missed all of last season after playing in 14 games in 2018 and finishing with six sacks, which was second on the team. He missed 30 of 32 regular-season games in 2016 and '17 because of suspensions. He has played in only 28 of a possible 80 regular-season games in his career.

The Cowboys selected Gregory in the second round in 2015 and have stood by him. The team had a short-term extension for Gregory blocked last year by the league because of the suspension.

ESPN's Todd Archer contributed to this report.