At the time, the "Jumanji" star also made a public note of condolence to Rob via Twitter. "Stay strong my friend. My ohana sends our love and light to you and your ohana," Dwayne wrote.
Meanwhile, Delaney described his son as "a very sweet, mischievous, funny boy" that "sensed right away that he would have to be very magnetic and adorable and attractive because our house was a zoo."
His late son was diagnosed with a tumor on his brain stem when he was one years old. After undergoing surgery to remove the mass, Delaney explained that the procedure had left him "seriously physically disabled but his frontal lobe wasn't affected so he was still very funny and mischievous."
The comedian and his wife Leah welcomed a fourth child six months after the tragic passing of Henry.
Waiting for your permission to load the Instagram Media.
The "Deadpool 2" star revealed that his son Henry was the inspiration behind his new book, "A Heart That Works" which helps other bereaved parents.
"It's not courageous, it's just what other bereaved people did for me and my wife," he said. "If I can write a book that can reach someone in a suburb of Yorkshire who can't get to a London bereaved parents meeting, then I've gotta do it."
Rob took to Instagram to thank his supporters for their "staggering response" after The Sunday Times published an excerpt from his book.
"I feel numerous things but one is that people have only seen the tiniest, tiniest sliver of Henry and our family's experience," he captioned the post. "I want to yell "Wait! You have to read the rest immediately!" I feel like people have walked into a tunnel and are stuck in there and need to read the rest of the book to get out."
Delaney continued, "I would also like to say that 100% of the money I earn from this book will be donated to children's hospices. Thanks to everyone reading."