The head of New Jersey's largest Catholic diocese promised Friday to be more careful when using social media after he mistakenly posted "Nighty-night, baby" on his public Twitter account.

Cardinal Joseph Tobin, who has been the head of the Archdiocese of Newark for more than a year, said he was sitting on a plane Wednesday night when he sent what he thought was a private Twitter message to one of his sisters.

When his plane landed two hours later, friends told him the message -- "Supposed to be airborne in 10 minutes. Nighty-night, baby. I love you." -- was posted on his public Twitter account.

Tobin, 65, said he immediately took the message down.

"However, the tweet continues to be widely diffused and has sown some misunderstanding," Tobin tweeted Friday. "I want to apologize to the priests and faithful of the Archdiocese of Newark, if my carelessness has caused any confusion or embarrassment. I promise to be more careful with future use of media."

Sitting on a plane last Wednesday evening, I mistakenly tweeted a message meant as a private communication with one of my sisters. When I arrived in Newark two hours later, friends informed me of the error and I immediately removed it. — Joe Tobin (@CardinalJWTobin) February 23, 2018

However, the tweet continues to be widely diffused and has sown some misunderstanding. I want to apologize to the priests and faithful of the Archdiocese of Newark, if my carelessness has caused any confusion or embarrassment. I promise to be more careful with future use of media — Joe Tobin (@CardinalJWTobin) February 23, 2018

Tobin has nearly 6,100 followers on Twitter. However, he uses the account sporadically for public posts. His last public post before his errant tweet to his sister was a photo of a church event in Indianapolis in November.

His "Nighty-night" message continued to whip around the internet Friday as some social media users chided him over the gaffe. Others encouraged Catholics not to use a misfired tweet to speculate about Tobin's personal life.

Don't you hate it when that happens? "Cardinal" Joe Tobin says this quickly-deleted tweet was meant for his sister: https://t.co/WHKb8woObT #catholic pic.twitter.com/pSua3uhyq6 — Novus Ordo Watch (@NovusOrdoWatch) February 23, 2018

The cardinal does not plan to comment further about the tweet beyond the apology he posted on his account, said James Goodness, a spokesman for the Archdiocese of Newark.

Tobin is the head of the archdiocese's nearly 1.5 million Roman Catholics in Essex, Union, Hudson and Bergen counties.

The Detroit native grew up as one of 13 children in an Irish-Catholic family and was previously the Archbishop of Indianapolis.

Tobin is a long-time friend of Pope Francis and is known as a moderate church leader who often uses self-deprecating humor while preaching.

At his introductory press conference in Newark he said he considered humor an essential part of his faith.

"If we take ourselves too seriously, we risk falling into either arrogance or despair," Tobin said.

Kelly Heyboer may be reached at kheyboer@njadvancemedia.com. Follow her on Twitter @KellyHeyboer. Find her at KellyHeyboerReporter on Facebook.