Ibn Abbas (may Allah be pleased with them both) said regarding «لعمرك‏» that by this is meant «لعيشك‏» .

Narrated Az-Zuhri: I heard `Urwa bin Az-Zubair, Sa`id bin Al-Musaiyab, 'Alqama bin Waqqas and 'Ubaidullah bin `Abdullah narrating from `Aisha, the wife of the Prophet, the story about the liars who said what they said about her and how Allah revealed her innocence afterwards. Each one of the above four narrators narrated to me a portion of her narration. (It was said in it), "The Prophet stood up, saying, 'Is there anyone who can relieve me from `Abdullah bin Ubai?' On that, Usaid bin Hudair got up and said to Sa`d bin 'Ubada, La`Amrullahi (By the Eternity of Allah), we will kill him!' "