Chronicles I 28:20

20 And David said to Solomon his son, Be strong, and play the man, and do: fear not, neither be terrified; for the Lord my God with thee; he will not forsake thee, and will not fail thee, until thou hast finished all the work of the service of the house of the Lord. And behold the pattern of the temple, even his house, and its treasury, and the upper chambers, and the inner store-rooms, and the place of propitiation, and the plan of the house of the Lord.

Chronicles I 28:20 Meaning and Commentary

1 Chronicles 28:20

And David said to Solomon his son, be strong, and of good
courage, and do it (See Gill on 1 Chronicles 28:10)

fear not, nor be dismayed;
that thou shalt meet with any opposition in the work, or not be able to finish it for want of materials and workmen, or money to pay them:

for the Lord God, [even] my God, will be with thee;
to guide and direct, prosper and succeed; the Targum is,

``the Word of the Lord God, my God, will be thy help:''

he will not fail thee, nor forsake thee;
a promise made to Joshua, and is applicable to every good man in whatsoever good work he is concerned, ( Joshua 1:5 ) ( Hebrews 13:5 ) ,

until thou hast finished all the work for the service of the house of
the Lord;
built the temple, and all the apartments of it, and courts belonging to it, and made and provided all the utensils and vessels necessary for the service and worship of God.

Chronicles I 28:20 In-Context

18 And he shewed him the weight of the altar of incense, of pure gold, and the plan of the chariot of the cherubs that spread out their wings, and overshadowed the ark of the covenant of the Lord.
19 David gave all to Solomon in the Lord's handwriting, according to the knowledge given him of the work of the pattern.
20 And David said to Solomon his son, Be strong, and play the man, and do: fear not, neither be terrified; for the Lord my God with thee; he will not forsake thee, and will not fail thee, until thou hast finished all the work of the service of the house of the Lord. And behold the pattern of the temple, even his house, and its treasury, and the upper chambers, and the inner store-rooms, and the place of propitiation, and the plan of the house of the Lord.
21 And see, the courses of the priests and Levites for all the service of the house of the Lord, and with thee for every workmanship, and every one of ready skill in every art: also the chief men and all the people, for all thy commands.

The Brenton translation of the Septuagint is in the public domain.