It was narrated from Ubayy bin 'Imarah, in whose house the Messenger of Allah performed prayer facing both prayer direction, that :
He said to the Messenger of Allah: Can I wipe over my leather socks? He said: Yes. He said: For one day? He said: For two days? He said: For three? And so on, until the number reached seven. He (the Prophet) said: For as long as you see fit.