Adjective to describe something that is not rushed

The word 'measured' would be appropriate, and particularly appropriate for the chosen example sentence.

b. Of aspects of language: carefully weighed or calculated; regulated, moderated, restrained. Of a person: using language in a careful, restrained way.

OED

We should be measuring our words carefully because we will have to give an account for them someday.

Bible Verses About The Power of Words

'Measured' implies thoughtful preparation and also implies care about content as stated in Ecclesiastes :

Be not rash with thy mouth, and let not thine heart be hasty to utter any thing before God: for God is in heaven, and thou upon earth: therefore let thy words be few.

Ecclesiastes 5:2 :

Consider unhurried or unrushed. The former is more common.

unhurried: Moving, acting, or taking place without haste or urgency. OD

unrushed: Characterized by an absence of haste; unhurried. OD

You can find examples of unhurried prayer (and the less common unrushed prayer) also.

How many of us compensate, for lack of unhurried prayer time, by having “popcorn prayer time” or “flash prayers” throughout our day as a substitute?

_{https://inspirationandhope.wordpress.com/tag/prayer-cannot-be-rushed/}

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The tighter the tension, the more time must there be for unhurried prayer.

_{Quiet Talks on Prayer (by S. D. Gordon)}

Other possible options are deliberate or thorough.

The word that comes to mind is meticulous as the opposite of rushed would be to do things slowly (and there seems implication that there should be an element of attention to detail and care in executing these processes), thus according to meticulous' definition it should fit

Meticulous: showing great attention to detail; very careful and precise.

Source: http://www.dictionary.com/