SAN FRANCISCO (AP) — Major League Baseball has warned players about writing on their uniforms after San Francisco starter Landen Roupp and two other pitchers added Bible verses to their Pride Night caps last week.

Roupp started the 5-1 loss to the Chicago Cubs on Friday night with “Gen 9:12-16” written on his cap. A portion of the Bible verse overlapped the rainbow SF logo players wore for the Pride Night. San Francisco relievers JT Brubaker and Ryan Walker also added Bible verses to their caps.

Another Giants pitcher, left-hander Sam Hentges, wore the team’s standard black cap with the orange logo instead of the Pride Night version.

MLB issued a warning about future violations of the league’s uniform policy.

“The writing on the cap violates our rules and consistent with normal practice we have warned the players about future violations,” MLB said in its original statement.

The league issued another statement Tuesday to elaborate.

“To be clear, this routine verbal warning not to wear the hat in future games is not disciplinary and had absolutely nothing to do with the content of the message,” MLB said.

“We respect players’ right to free expression. However, writing of any kind, with any message, is prohibited per Major League Baseball’s Uniform Regulations which provides in part that, ‘(a) Player may not write, attach, affix, embroider or otherwise display nicknames or messages on apparel or playing equipment…’. We have given the same warning numerous times in the past to players for messages such as ‘Dad’, ‘Happy Mother’s Day, I Love Mom,’ and names of family members.”

MLB teams sometimes host Pride Nights during the regular season to support their LGBTQ+ fans. The league has been a leader among the four major U.S. pro sports in hosting Pride Nights, in part because its regular season overlaps with Pride Month in June. Many adopt rainbow-colored uniforms patches or logos, set up special signage around ballparks and invite guests including community leaders and drag performers.

The portion of the Genesis verse cited by Roupp on his hat included God’s promise to never again send a worldwide flood and the rainbow in the sky is the sign of that covenant.

“That’s just kind of something I believe in, and I stand firm in that, and I’m thankful we live in a country where, you know, we have the freedom to believe what we want … and express what we want,” Roupp told reporters.

Giants manager Tony Vitello told reporters nothing was discussed with the pitchers before the game. Vitello said it was “just kind of a general knowledge” that players “have the freedom to do what they think is best.”