Sampasadaniyasutta 10.6

10.6

Tatra, bhante, yāyaṃ paṭipadā dukkhā dandhābhiññā, ayaṃ, bhante, paṭipadā ubhayeneva hīnā akkhāyati dukkhattā ca dandhattā ca.

Of these, the painful practice with slow insight is said to be inferior both ways: because it’s painful and because it’s slow.