Hello, Silver. That's a good question. This would be something you would express to someone who is having a difficult time. You might say, "all my prayers are with you" if someone has faced a tragedy like an illness or the death of a family member. You are telling that person they will be included in all of your prayers.

Hello, "all of my prayers are with you" is used when someone is trying to express that they are wishing the best for you through prayer or that they are praying for you in a time of sadness.

It seems a little weird for me.. it's like a mix of 'I'm praying for you'/'You are in my prayers' and 'My thoughts are with you', I would say. :)