Khloé Kardashian gushes over 'incredible rare bond' as she celebrates sister Kourtney's 40th birthday

Khloé Kardashian shared a series of snaps with sister Kourtney to celebrate her 40th birthday on Thursday, including some throwbacks.

Khloé posted a slew of images to her Instagram alongside a heartfelt caption about the “incredible rare bond” the duo share.

“Happy birthday sweet @kourtneykardash!!! I am completely obsessed with each and every one of my siblings,” Khloé wrote. “Still blows my mind how blessed we are to call each other sisters. You and I have an incredible rare bond that no matter what, it can never be broken.

“You’re my best friend, one of the rare few I can count on most in my life. I’m so thankful for that […] Honestly, without you my life would be boring and not as full.”

Khloé also told her sister that she “prays her soul is awakened” and that she finds happiness and “magical things” for the rest of her life.

Among the snaps were shots of the sister’s posing for photos and selfies as well as one of a teenage Kourtney next to a massive bouquet of balloons.

Famous matriarch Kris Jenner also used Instagram to share a special birthday tribute to her eldest child on her big birthday.

“Happy Birthday Kourtney!!! I can’t believe you are 40!! I love you more than you can ever imagine...you will always be my baby,” Jenner wrote. “I am so blessed beyond words to be your Mommy and have you by my side in this precious life. You are my heart and I am eternally grateful for all of the memories that we cherish. I love you. Mommy xoxo.”

The head of the Kardashian-Jenner clan posted a variety of snaps of the pair laughing and joking, even sharing some throwback snaps to Kourtney’s childhood and one with her late father Robert Kardashian.

Kourtney’s brand Poosh also paid tribute to its founder, creating a video of “hilarious and sentimental” stories involving the star.