Deuteronomy 11:21

21 that the days of thee and of thy sons be multiplied in the land which the Lord swore to thy fathers, that he should give to them, as long as heaven is above (the) earth. (so that the days of thee and of thy sons, can be multiplied in the land which the Lord swore to thy fathers to give them, for as long as the heavens be above the earth.)

Deuteronomy 11:21 Meaning and Commentary

Deuteronomy 11:21

That your days may be multiplied
Long life being a very desirable blessing, and which is promised to those that obey and keep the law; see ( Deuteronomy 30:19 Deuteronomy 30:20 ) ( Psalms 91:16 )

and the days of your children;
which are dear to parents, and the continuance of whose lives, next to their own, is most desirable, yea, as desirable as their own; and especially it is desirable that they might have a posterity descending from them, to enjoy for ever their estates and possessions; as it was to the people of Israel, that they might have a seed always to dwell

in the land which the Lord sware unto your fathers to give them;
the land of Canaan, so often spoken of as the promise, oath, and gift of God:

as the days of heaven upon the earth;
that is, as long as the heavens and the earth shall be, and the one shall be over the other, as they will be to the end of time.

Deuteronomy 11:21 In-Context

19 Teach ye your sons, (so) that they think upon those words, when thou sittest in thine house, and goest in the way (and goest on the way), and liest down, and risest up.

20 Thou shalt write those words upon the (door-)posts, and the gates of thine house(s),

21 that the days of thee and of thy sons be multiplied in the land which the Lord swore to thy fathers, that he should give to them, as long as heaven is above (the) earth. (so that the days of thee and of thy sons, can be multiplied in the land which the Lord swore to thy fathers to give them, for as long as the heavens be above the earth.)

22 For if ye keep the behests which I command to you, and do those (For if ye obey all these commandments which I command to you, and do them), that ye love your Lord God, and go in all his ways, and cleave to him,

23 the Lord shall destroy all these heathen men before your face, and ye shall wield those folks that be greater and stronger than ye.