Tractate Shevuot - Chapter 8 - Mishnah 3 שבועות פרק ח׳ משנה ג׳

[If the owner said,] “Where is my ox?” and he replied to him, “I do not know what you are talking about,” whereas in reality it died or was injured or captured or stolen or lost, [and the owner said,] “I adjure you,” and he said, “Amen”, he is exempt. [If the owner said,] “Where is my ox?” and he replied to him, “It was lost”; [and the owner said,] “I adjure you”, and he said, “Amen”, and witnesses testify against him that he had consumed it, he pays the principal; if he confessed himself, he pays the principal, a fifth, and brings a guilt-offering. [If the owner said,] “Where is my ox?” and he replied to him, “It was stolen;” [and the owner said,] “I adjure you, and he said, “Amen”, and witnesses testify against him that he himself stole it, he pays double; if he confessed himself, he pays the principal, fifth, and brings a guilt-offering.