Sahih Muslim Book 9, Hadith Number 3542.

Chapter: It is obligatory to abstain from adornment during the ‘Idda period, but mourning beyond three days is prohibited.

Humaid b. Nafi’ narrated two traditions from Umm Salama dealing with collyrium and the other hadith from the wives of Allah’s Prophet (may peace be upon him) except with this that no mention was made of Zainab.