1 Timothy 1:17 New English Translation

¹⁷Now to the eternal king,^[a] immortal, invisible, the only^[b] God, be honor and glory forever and ever!^[c] Amen.

1 Timothy 1:17 tn Or more literally, “king of the ages.”
1 Timothy 1:17 tc Most later witnesses (א² D¹ H^c Ψ 1175 1241 1881 M al) have “wise” (σόφῳ, sophō) here (thus, “the only wise God”), while the earlier and better witnesses (א* A D* F G H* 33 1739 lat co) lack this adjective. Although it could be argued that the longer reading is harder since it does not as emphatically affirm monotheism, it is more likely that scribes borrowed σόφῳ from Rom 16:27 (Rom 14:26 in M) where μόνῳ σόφῳ θεῷ (monō sophō theō, “the only wise God”) is textually solid. It is difficult to explain why Alexandrian and Western scribes would omit “wise” in 1 Tim 1:17 while keeping it in Rom 16:27 for a similar benedition.
1 Timothy 1:17 tn Grk “unto the ages of the ages,” an emphatic way of speaking about eternity in Greek.

New English Translation (NET)