Tatmainn is interpreted in three senses:
1. Tatmainn is used in the sense of finding tranquility, as in the following verses:
But [I ask] only that my qalb (the heart) may be mutmaʾinn (find tranquility) {that is, that by looking at it my qalb may find peace}... (al-Baqara 2:260)
So that our qulub (hearts) may be mutmaʾinn (i.e., that by seeing the table You will send, our hearts may find peace). (al-Māʾida 5:113)
They are those who have iman (faith) and whose qulub are mutmaʾinn with the dhikr (remembrance of Allah). Verily, in the dhikr of Allah do qulub become mutmaʾinn (i.e., hearts find tranquility). (al-Raʿd 13:28)
Allah did this (i.e., on the Day of ʿUqud, sending the angels to your aid) only as a glad tiding and so that your qulub may be mutmaʾinn thereby (i.e., so that your hearts may find peace). (Āl ʿImrān 3:126)
Allah did this only as a glad tiding for you and so that your qulub may be mutmaʾinn thereby (i.e., so that your hearts may find peace). (al-Anfāl 8:10)
2. Itmaʾanna is used in the sense of riḍā (contentment) or being pleased, as in the following verses:
If good befalls him, he is mutmaʾinn (i.e., content, pleased) with it. (al-Ḥajj 22:11)
Except for those who are compelled while their qalb is mutmaʾinn with iman (i.e., content/pleased)... (al-Naḥl 16:106)
O mutmaʾinna (i.e., one who is content/pleased with Allah's reward)... (al-Fajr 89:27)
3. al-Itmiʾnāniyya is used in the sense of residing or being settled, as in the following verses:
Then when you have become mutmaʾinn (i.e., when you have transitioned from a state of travel to a state of residence/settlement), establish the salat (prayer) (i.e., perform the prayer in full, not shortened)! (al-Nisāʾ 4:103)
Say: "If there were angels walking about on the earth mutmaʾinn (i.e., settled, residing)..." (al-Isrāʾ 17:95)