All the wives of the Prophet salla Allahu alaihi wa sallam wore the hijab.
The evidence of this is from the Quran and the Sunnah.
“And when you ask (his wives) for anything you want, ask them from behind a screen: that is purer for your hearts and for their hearts. And it is not (right) for you that you should annoy Allâh’s Messenger, nor that you should ever marry his wives after him (his death). Verily, With Allâh that shall be an enormity.” 33:53
“O Prophet! Tell your wives and your daughters and the women of the believers to draw their cloaks (veils) all over their bodies (i.e. screen themselves completely except the eyes or one eye to see the way). That will be better, that they should be known (as free respectable women) so as not to be annoyed. And Allâh is Ever Oft-Forgiving, Most Merciful.” 33:59
As for the Sunnah, in the story of Ifk, where Aisha may Allah be pleased with her said that Sawfwan may Allah be pleased saw her before the Hijab was mandated and he recognized her.
There are a number of other evidences as well.
And Allah knows best