Jabir bin Zayd narrates from Ibn Abbas (may Allah be pleased with them both) that he was asked about a woman who had testified that she had breastfed a woman and her husband. He said: Make her swear an oath near the Station of Ibrahim; if she is lying, a year will not pass before her breasts turn white. She was made to swear and she swore, and within a year her breasts turned white.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الشهادات / 20699