Britney Spears Shared a Throwback Picture Featuring Justin Timberlake for Jamie Lynn's Birthday

• In a sweet Instagram post this weekend, Britney Spears celebrated her younger sister Jamie Lynn's 30th birthday.
• The 39-year-old singer shared a heartfelt, belated birthday message for her sister, who turned 30 on April 4. Britney included a throwback picture from 2001 with the post and her ex-boyfriend, Justin Timberlake, is in the photo.
• "I love you so much and damn it I wish I was as smart as you at 30 !!!! It's weird to say that I was basically your momma when you were younger and yes I'm still older but your soul is and always has been wise !!!! I’m truly and genuinely inspired by your path and the life you have created for your beautiful children and I'm so f*cking proud to call someone as beautiful inside as you my sister !!!!

Britney Spears is celebrating one of her younger sister, Jamie Lynn's, milestone birthdays.

The singer shared a sweet (albeit slightly belated) tribute to Jamie Lynn on Instagram this weekend in honor of her 30th birthday, which was earlier this month, on April 4. While it's no surprise to see Britney publicly doting on her little sister, another person from Brit's past made a more surprising appearance in the post: Justin Timberlake.

The picture shows a young Jamie Lynn looking very Y2K in small purple-tinged, oval-shaped glasses and a fun mixed-print top. She's surrounded by smiling loved ones, including Britney and her then-boyfriend, Justin. 

"Happy belated birthday to this beautiful soul 🎂🎂🎂 !!!" Britney gushed in the post's caption. "I love you so much and damn it I wish I was as smart as you at 30 !!!! It's weird to say that I was basically your momma when you were younger and yes I'm still older but your soul is and always has been wise !!!! I’m truly and genuinely inspired by your path and the life you have created for your beautiful children and I'm so f*cking proud to call someone as beautiful inside as you my sister !!!! And not only are you a beautiful soul you're so DAMN STRONG ... I was extremely taken back and still am to this very day !!! We play wrestled at home (such classy Southern chicks) 🐣🙄😹🤷🏼‍♀️🤷🏼‍♀️ and you put me to the floor in literally two seconds after I gave all my might 😜😜😜😹😹😹 … I’ll never forget it !!! Maybe we should have a rematch 🙊💪🏼🥊 ... I mean things have changed since 6 years ago 💋 💋💋!!!!! PS I wish I was as strong as you and happy birthday 🎊 !!!!"

Britney and Justin dated from 1999 until 2002 and the picture in question appears to be from November 2001 and was taken at the launch of Britney's third album, Britney. Here's a picture of Justin protectively hugging Jamie Lynn at the same event: 

Justin recently publicly apologized to Britney after facing backlash following the release of the New York Times documentary Framing Britney Spears, which touched on his role in the media's poor treatment of the singer during the height of her fame in the early 2000s.

"I've seen the messages, tags, comments and concerns and I want to respond. I am deeply sorry for the times in my life where my actions contributed to the problem, where I spoke out of turn or did not speak up for what was right," he wrote in a lengthy Instagram post in which he apologized not just to Britney, but also to Janet Jackson, who faced grossly unequal backlash after her "wardrobe malfunction" during her 2004 Super Bowl performance with the former NSYNC singer.

"I understand that I fell short in these moments and in many others and benefited from a system that condones misogyny and racism," Justin's apology continued. "I specifically want to apologize to Britney Spears and Janet Jackson both individually, because I care for and respect these women and I know I failed. I also feel compelled to respond, in part, because everyone involved deserves better and most importantly, because this is a larger conversation that I wholeheartedly want to be part of and grow from."