"Prabhupada, what book will you translate after the Bhagavatam?"

Pradyumna Dasa recounts:

Srila Prabhupada always considered that 4 books were necessary: Bhagavad Gita, Srimad Bhagavatam, Bhakti Rasamrita Sindhu (Nectar of Devotion), and Caitanya Caritamrta.
And outside of that everything is really extra.

One time we were in New York, in Srila Prabhupada’s room. And I think it was Radha Ballabha who asked, “After you finish the Srimad Bhagavatam Prabhupada what book would you like to translate?

Srila Prabhupada answered, “Oh maybe… Jiva Goswami’s Sad Sandarbha … or Vedanta Sutra or… there’s so many…maybe Bhagavad Gita!”

And someone spoke up, “But... Srila Prabhupada, you already did the Bhagavad Gita!”

Srila Prabhupada responded with vigour, “We did the Bhagavad Gita but there are so many commentaries. We did part… We did a small.
There are so many commentaries: Ramanujacarya, Madhavacarya… everyone has given their Gita! We can do many Gitas! Not just one…”