Copied from Ven Paññadīpa.
Why can the Sotāpanna and Sakadāgāmi persons not enter upon the attainment of mental cessation (Nirodhasamāpatti)?
Nirodhasamāpatti is based on a pair of the tranquility and insight. The tranquility refers to the mundane absorption (Lokiyajhāna) which is the eight attainments (Samāpatti), such as four material absorptions (Rūpajhāna) through the fourfold method and four immaterial absorptions (Arūpajhāna). Insight refers to insight knowledge which sees the conditioned phenomena (Sańkhāras), such as consciousnesses and mental factors in each Jhāna, as impermanent, suffering, and non-self.
Whenever each Jhāna is entered upon from the first Rūpajhāna to the second Arūpajhāna and withdrawn from, Sańkhāras in each Jhāna are meditated on through insight knowledge. When the third Arūpajhāna is entered upon and withdrawn from, the four preliminary functions are performed without meditating on Sańkhāras in it. After that, the fourth Arūpajhāna is entered upon, and all the consciousnesses, mental factors, and mind-born matters come into cessation immediately after the fourth Arūpajhānajavana runs twice.
The opposite of those Jhānas is Kāmarāgānusaya (the dormant disposition of sensual lust) that the Sotāpanna and Sakadāgāmi persons haven’t totally yet eradicated. Hence, their jhāna-concentration isn’t as strong as that of the Anāgāmi and Arahant persons who have completely eradicated it. Therefore, the Sotāpanna and Sakadāgāmi persons can’t enter upon the attainment of mental cessation.
[Ref; Visuddhimagga Aṭṭhakathā-2; 344-350: Exposition of Process and Collection of Three Facts; 71-75: Dr. Nandamālābhivaṃsa’s Fundamental Abhidhamma-2; 104-105]