Jessica Simpson Says 'Generous' Daughter Maxwell Used Birthday Wish on Her Grandpa Joe's Cancer

"Maxwell's birthday wish was for her Papa Joe's bone cancer treatment to work. It did. Thank you Maxi Drew for usin' your wish on our family and most importantly, my Dad," Jessica Simpson wrote

Jessica Simpson is thanking her daughter Maxwell for using her birthday wish on a selfless cause.

The mom of three, 42, discussed Saturday on Instagram how her now 11-year-old wished for Jessica's father's bone cancer treatments to work.

Alongside a joyful photo of Maxwell holding up her mother, Jessica began her caption, "On May 1, 2012, my firstborn, Maxwell Drew Johnson, arrived into this life as a sentient being seemingly not of this world."

"In the purest of form, her mind heart and soul ascended from the grace of heaven to shine in profound ways," she wrote. "I felt her purpose in my life when I was a kid and I would pray for my future daughter every single day and night."

Related:Jessica Simpson Praises Daughter Maxwell for Giving Back on Christmas: 'Her Heart Is Beautiful'

Jessica continued, "I know that most Moms would say please slow down time when their baby turns 11, but I have truly known her my entire life. Reading back on 30 yrs of conversations with God throughout my journal entries, it is evident that Maxwell was already living inside of my heart and my purpose."

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The singer then shared how she celebrated her eldest's birthday, "Her birthday was FRANKLIN FARM LIFE HAPPY! She told me after she blew out HER 11 candles…'I made a wish that was for me and you and actually the whole family.' I said Maxi it should be your wish, and she said 'we have the same wishes Mom.'"

"Three days later on our way back to Cali she overheard me reading a text from my Dad and asked my mom sitting next to her 'GiGi if my birthday wish came true already can I say it out loud or do I still keep it to myself?'"

Related:Jessica Simpson Shares Rare Family Photo with Both of Her Parents: 'I Am Proud of Us'

"My mom told her to share it with everyone if she wanted to, especially if it had already come true," Jessica continued before revealing what exactly her daughter wished for.

"Maxwell's birthday wish was for her Papa Joe's bone cancer treatment to work. It did. Thank you, Maxi Drew, for usin' your wish on our family and most importantly, my Dad," she shared.

Concluding her caption, Jessica said of her daughter, "You are mesmerizing, steadfast, intelligent, passionate, generous, loving, devoted, inspiring, enticing, confident, empathetic, powerful, intuitive, beautiful, DETERMINED, enlightened and FULL OF WONDER. The faith of a child is what keeps all of us ALIVE."

Joe Simpson, 65, was initially diagnosed with prostate cancer in September 2016 and confirmed the news in November of that year. He was declared cancer-free in May 2017.

Jessica shares Maxwell with husband Eric Johnson, along with son Ace, 9, and daughter Birdie Mae, 4.

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