Source, in full
Uttered as Louis Bourdaloue rose to deliver a sermon at Saint-Sulpice, Paris. Quoted in P. M. Lauras Bourdalou: sa vie et ses oeuvres (1881), vol. 2, p. 72. Translated in Edwin Charles Dargan, A History of Preaching (New York, 1912), vol. 2, p. 100
Variants
voici for voilá