We report a precision frequency measurement of the transition at 2058 nm. <?format ?>The saturated absorption spectroscopy is performed in a rf discharge sealed-off cell with a volume Bragg grating-based Tm:Ho:YLF laser. The absolute transition frequency measured using a fiber optical frequency comb is 145 622 892 822 (183) kHz with a relative uncertainty of . Our result is ten times more precise than current best theoretical calculations and is in reasonable agreement with the calculated values. However, the ionization energy of the state, derived from our result and other precisely measured transitions, shows a discrepancy of approximately with the most precise atomic theory. We have also determined the isotope shift between and to be 4248.7 (5.3) MHz, which <?format ?>is more precise than the previous measurement by one order of magnitude.