This is an odd one. I’m back in the mysterious miscellaneous folder of Church songs and this is an ancient song that appears to have been part of a musical drama for children, but I think we used it as a sort of mantra. It has not been spotted for a very long time. It is by Harry D. Clark and was originally published in the 1920s. You can download the sheet music from the publisher here. This is a solo vocal version.
Into my heart, into my heart.
Come into my heart, Lord Jesus.
Come in today, come in to stay.
Come into my heart, Lord Jesus.