"An arhat, seeking refuge in the Buddha, is afraid. Why? An arhat lives in fear of the imminent state of nothingness, as if it were a man holding a sword coming to cause him harm. Therefore, the arhat does not have ultimate happiness."
Srimaladevi Simhanada Sutra (CBETA, T12, no. 353, p. 219, b26)
"All practitioners of Two-Vehicle Buddhism are afraid that there will be nothing left of them after they enter nirvana. They are fearful of total annihilation and they cannot help but harbor a bit of apprehension. Although the Buddha states that entering remainderless nirvana does not entail total annihilation, they still feel uneasy since they cannot verify this fact themselves. Therefore, they are still fearful of the complete extinction of their aggregates [skandhās], sense-fields [ayatanās] and sense-realms [dhātavas]. However, regardless of this fear, in order to attain the remainderless nirvana, they still have to enter a state of nothingness resulting from the elimination of the aggregates, sense-fields and sense-realms. From the arhats’ viewpoint, the five aggregates are enemies, foes, carbuncles, thorns, killers and ought to be extinguished. The five aggregates are like a man holding a sword intending to cause harm. Indeed they will bind a person to uninterrupted cyclic existence for uncountable eons. But what will be left in the remainderless nirvana once the five aggregates are extinguished? The Two-Vehicle practitioners have no idea. The Buddha says the essence of the remainderless nirvana is real, immutable, and permanent. But what is really inside the remainderless nirvana? The arhats remain in the dark. For these reasons, the arhats do not have ultimate happiness."
A Discourse on the Srimaladevi Simhanada Sutra, Vol. 2, pp. 24-25
“It is difficult for the correct dharmas to manifest if the erroneous ones are not destroyed 若不破邪，難以顯正.” Bodhisattva Xuanzang (玄奘菩薩) stated in the past.