Sayyiduna Ibn Abbas (may Allah be pleased with them both) said: When a proposal of marriage was made for one of the daughters of the Prophet (peace and blessings be upon him), he (peace and blessings be upon him) would come to the curtain and say: "So-and-so is proposing to so-and-so." If she struck the wall (as a sign of refusal), he (peace and blessings be upon him) would not marry her off, and if she did not strike the wall, he would marry her off.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11949