It doesn't happen often, but it does happen — people see my son Paul and ask if they can pray for him.
At places like WalMart (where it has happened) I usually accept their offer after quietly and quickly assessing their motives and authenticity. And people are usually appropriate.
But a scenario occurred recently where I struggled to respond graciously. The Holy Spirit helped me in that moment as I could feel my pride being challenged. Here’s the story. 

A Prayer for Healing

We got to our church service a few minutes late. I plopped Paul down in the seats just outside the sanctuary while we got our bearings on who was going where. A gentleman noticed Paul and asked me what "disease" he had. I quickly told him that Paul is blind and autistic (I only give the full list when we have more time) and he asked if he could pray for healing. He said God heals people from blindness and he’s seen it.
People pray for Paul all the time at church, but generally don’t make such bold pronouncements about healing. I accepted his offer and he proceeded to ask for Paul to be healed of his blindness and his autism right there, through the power of the Holy Spirit and in Jesus’ name. It was very sweet, this stranger praying so fervently for my son.
But my own spirit was not seeing the sweetness then and I was getting irritated. Didn’t he think God created some like Paul just the way he is? Didn’t he think I had faith? Didn’t he think I prayed for my son?
He finished and said that he believed God could heal my son and was genuinely disappointed that nothing had happened. I responded that I knew God could heal him, but sometimes God is more clearly present in the sustaining grace and peace he grants when he doesn’t choose to heal in this age.
And that was it. I entered the sanctuary and didn’t see this gentleman again.

Greater Glory and Greater Help

My wife helped me understand what happened in its proper context: this gentleman saw a need and his immediate reaction was to pray.  He wasn’t challenging my faith or accusing me of anything, he just wanted to pray. He believed God could move.
And God answers prayer! Yet, God sometimes brings greater glory to himself — and greater help to his church — when he doesn’t do exactly what we ask of him. The one who knows the end from the beginning is in a much better place to determine how to answer the prayers of his saints. And he is always good, always just, always right, and always capable to do what he has promised.
I’ve decided that I’m glad this gentleman prayed, even if my heart wasn’t exactly right in the moment. And I hope he heard me — that I helped him see God’s sustaining grace is also a wonderful thing, that God's sustaining grace in this age is not at all a lesser gift than healing.
Maybe, in fact, it is a greater gift because we have less temptation to forget how weak we are. We are so utterly dependent on God's daily, continual help.