Surah Al-Mursalat 77:21

فَجَعَلْنَـٰهُ فِى قَرَارٍ مَّكِينٍ

And We placed it in a firm lodging [i.e., the womb]

Translation: Saheeh International

Tafsir

then lodged it in a secure abode that is the womb

Excerpt from Tafsir al-Jalalayn, commentary on 77:21, via Quran.com. The reader has the full commentary and 9 more tafsirs.