Selena Gomez and Courtney Barry (c) Instagram

Selena Gomez and her closest group of pals all had the number four etched onto their skin while having a girl's night to mark Courtney Barry's 26th birthday over the weekend.

The 'It Aint Me' singer posted a series of photos on Sunday with Courtney, Raquelle Stevens, and Ashley Cook, posing and eating pizza and ice cream together. 

My best friend turned 26. Part one.

A post shared by Selena Gomez (@selenagomez) on

She also revealed her new body art by posting a photo of her having a tattoo done on her arm while she smiled in a selfie. 

She wrote: "Best friend turned 26. Part 2. #4 because these women have stayed by my side for 7 years (@ashley_cook 12 years) 4, because you are my 4 for the rest of my life..."

Selena, 26, ended her tribute by posting a picture of her and best friend Courtney, holding up their T-shirts to reveal their matching ink. 

She wrote: "And lastly, my actual #[email protected] you are an incredible woman. The way you handle life's most confusing moments is indescribable and graceful...."