John 11:41

So they took away the stone. And Jesus lifted up his eyes, and said, Father, I thank thee that thou heardest me always: but because of the multitude that standeth around I said it, that they may believe that thou didst send me.

They took away the stone ... See under John 11:39. This second command was obeyed at once, there being no further objection from Martha.

I thank thee that thou heardest me always ... All of the miracles done by Jesus, it may be supposed, were done through answer to his prayers. Jesus himself, as a Person of the Godhead, was all-powerful; but all of his earthly deeds were accomplished under the limitations of our earth life. As the great example to men, even if Jesus might have done signs without calling on the Father, it was highly appropriate for him to have done all things with constant regard of the Father's will. Those closest to Jesus knew this, as witness the words of Martha (John 11:22), and the conclusion of the blind man (John 9:31).

That they may believe ... Those who would take this word from Jesus and make it the basis of addressing admonitions to the audience in a public prayer might be justified, if they truly follow Jesus' example by performing a miracle immediately afterward! Note too that Jesus addressed not the audience but the Father. The privilege of the multitude in hearing such a prayer, thanking God in advance for Lazarus' resurrection, added superlative weight to the sign itself.