Justin Timberlake insisted he only had one drink following DWI arrest

Musician Justin Timberlake was arrested on June 18 on DWI charges after spending an evening with friends at the American Hotel in Sag Harbor. The 43-year-old singer, known for his hit "Selfish," was held overnight ahead of his arraignment.

A source told PEOPLE, "He was freaking out and stayed up all night when he was in custody. He's insisting he only had one drink and it wasn't some wild night out." Timberlake reportedly told the arresting officer, "I had one martini and I followed my friends home."

Despite the arrest, Timberlake will continue his "Forget Tomorrow World Tour" as planned, with upcoming performances in Chicago on June 21 and 22, and in New York City on June 25 and 26. "It’s business as usual for him," the source added.

Timberlake was charged with one count of driving while intoxicated and received citations for running a stop sign and failure to keep in lane. The arrest report noted that his "eyes were bloodshot and glassy."

Another source confirmed to PEOPLE that Timberlake had been "hanging out with friends." Timberlake refused multiple times to take a chemical test and was taken to Sag Harbor Police Headquarters, where he stayed overnight before being released the next morning.

Timberlake’s attorney, Edward Burke Jr., stated, “Mr. Burke looks forward to vigorously defending Mr. Timberlake against these allegations. He will have a lot to say at the appropriate time. He is currently awaiting full discovery from the DA’s office."

Timberlake’s court hearing is set for July 26, coinciding with his scheduled performance at the Tauron Arena in Kraków, Poland.