Volume 1, Book 3, Number 95:

Narrated Anas:

Whenever the Prophet spoke a sentence (said a thing), he used to repeat it thrice so that the people could understand it properly from him and whenever he asked permission to enter, (he knocked the door) thrice with greeting.

Volume 1, Book 3, Number 97:

Narrated Abu Burda’s father:

Allah’s Apostle said “3 persons will have a double reward:

1. A Person from the people of the scriptures who believed in his prophet (Jesus or Moses) and then believed in the Prophet Muhammad (i .e. has embraced Islam).

2. A slave who discharges his duties to Allah and his master. 

3. A master of a woman-slave who teaches her good manners and educates her in the best pos- sible way (the religion) and manumits her and then marries her.”

Volume 1, Book 3, Number 101:

Narrated Abu Said Al-Khudri:

Some women requested the Prophet to fix a day for them as the men were taking all his time. On that he promised them one day for religious lessons and commandments. Once during such a lesson the Prophet said, “A woman whose three children die will be shielded by them from the Hell fire.” On that a woman asked, “If only two die?” He replied, “Even two (will shield her from the Hell-fire).”