If anyone of you prays after the Friday prayer, he should say for rak'ahs. According to the version of the narrator Ibn Yunus, the tradition goes: When you have offered the Friday prayer, pray after it four rak'ahs. He said: My father said to me: My son, if you have said two rak'ahs in the mosque, then you comes to your house, pray two rak'ahs more.
Sunan Abi Dawud Book 2, Hadith 742