It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Surely Sayyiduna Ibrahim (peace be upon him) said only three times something that outwardly seemed to be untrue, two of which were for the sake of Allah: (first) his saying: 'I am ill', and (second) his saying: 'Rather, this one, the biggest of them, did it' (meaning the biggest idol). And (the third incident is that) he passed through a land in which there lived one of the tyrant kings, and Sayyidah Sarah (may Allah be pleased with her) was with him. That king sent (someone) to him (to ask): 'Who is this woman to you?' He said: 'She is my sister.' Then he sent (an order) to him: 'Send her to me.'"
Hadith Referenceالمعجم الأوسط / باب الألف / 956
Hadith Takhrij«أخرجه البخاري فى «صحيحه» برقم: 2217، 2635، 3357، 3358، 5084، 6950، ومسلم فى «صحيحه» برقم: 2371، وابن حبان فى «صحيحه» برقم: 5737، والنسائي فى «السنن الكبرى» برقم: 8315، 8316، 8317، وأبو داود فى «سننه» برقم: 2212، والترمذي فى «جامعه» برقم: 3166، والبيهقي فى «السنن الكبرى» برقم: 15246، 15247، 20892، وأحمد فى «مسنده» برقم: 9364، وأبو يعلى فى «مسنده» برقم: 6039، والبزار فى «مسنده» برقم: 9980، 10054»