Nyingtig Yabzhi

Nyingtig Yabzhi (snying thig ya bzhi). One of the most famous collections of Dzogchen scriptures.

The Four Branches of Heart Essence are highly respected and famous under the Tibetan name Nyingtig Yabzhi. These two sets of Heart Essence—the Khandro Nyingtig (Heart Essence of the Dakinis) of Padmasambhava and the Vima Nyingtig of Vimalamitra—has each a Quintessence written by Longchenpa, the Khandro Yangtig (Quintessence of the Dakinis) and Lama Yangtig (Quintessence of the Guru). In addition, there is the Profound Quintessence (Zabmo Yangtig). Together these are called the Mother and Child Heart Essence (Nyingtig Mabu).
Tulku Urgyen Rinpoche, in Blazing Splendor

Vimalamitra united the two aspects of Innermost Unexcelled Section - the explanatory lineage with scriptures and the hearing lineage without scriptures - and concealed them to be revealed as the Nyingtig teachings Vima Nyingtig, and also as the Secret Heart Essence of Vimalamitra (bi ma'i gsang ba snying thig). Longchenpa clarified them in his 51 sections of Lama Yangtig.

Padmakara concealed his teachings on the Innermost Unexcelled Cycle to be revealed in the future as Khandro Nyingtig, the Heart Essence of the Dakinis. Longchenpa also clarified these teachings in his Khandro Yangtig.

These four exceptional sets of Dzogchen instructions are, together with Longchenpa's additional teachings Zabmo Yangtig, contained in his collection, Nyingtig Yabzhi.

Four Branches of Heart Essence, the—(Nyingtig Yabzhi) One of the most famous collections of Dzogchen scriptures, in which Longchenpa combined the streams of teachings from Padmasambhava and Vimalamitra together with his own mind treasures.

from the Rangjung Yeshe glossaries