R. Meir hearing a voice that ordered a serpent to kill Judah ha-Nassi ran ahead of it, reached the house, closed doors and windows and prayed intently. The serpent unable to enter, coiled round the house till a voice from Heaven proclaimed R. Meir's prayer to be granted, when it departed.
How Rabbi Meir Talked a Serpent Out of Killing Judah HaNasi
Gaster, Exempla No. 314