Three types of Words of the Buddha

There are three types of words of the Buddha (Tib. ka sum), in terms of their medium of transmission (Wyl. bdag rkyen) sometimes translated as the "three transmitted precepts". They are:

1. the oral teachings (Tib. sungwé ka);
2. the teachings given through blessings (Tib. chinji labpé ka), as when while in meditation the Buddha blessed Avalokiteshvara and Shariputra and the Heart Sutra arose; and
3. the repeated teachings (Tib. rjes su nangwé ka), at the beginning of which teaching it says, "Thus have I heard" and at the end, "This is how the Buddha spoke".

Source

RigpaWiki:Three types of Words of the Buddha