Justin Bieber had the sweetest message for his longtime friend, Jaden Smith, on his 23rd birthday.The “Peaches” singer took to social media to let Smith know just how much he means to him, writing a heartfelt message about his humanitarian and philanthropic efforts making the world a better place.“Happy birthday to my brother and best friend @c.syresmith,” he wrote on Instagram under a picture of the “Summertime in Paris” singer wrapping his arms around him.