3. It is obtained from a Perfect Master:

He to whom the Lord is kind meets a perfect Master, and obtains from Him the Divine Ambrosia. By the Ambrosia of the Name the soul of a disciple becomes fragrant and enraptured. It forgets all the tasteless pursuits of the world and becomes absorbed in the music of the Naam.

One gets the Divine Ambrosia through His Grace, when one meets a perfect Master. Oh  Nanak, all other tasteless pleasures are forgotten; when the Lord dwells in the heart.

Ramkali M3, 921-11

Fortunate is the one who meets the Master, in his heart is the Naam; and he enjoys the Divine Ambrosia.

Gauri M3, 162-2

Oh Master! enshrine within me the sweet Naam of the Lord, which is cool and fragrant like the sandalwood. The Naam has wholly illumined my mind and the gaze of my soul sees all.

Nat M4, 981-5

How to find the Lord, oh Saints, by seeing Whom I become alive? I cannot live for a moment without Him. Unite me with the Master that I may taste the Divine Ambrosia.

Gauri M3, 163-9

Through the mercy of the Master, one receives the food of Love, then one loses the taste for everything else and enshrines the Divine Ambrosia in his heart.

Majh M3, 115-14

Sweet is the Name of the Lord, oh dear one; taste it with your whole mind; taste the Divine Ambrosia, forsaking all other tastes.

Gauri M3, 246-13