Commercial finite element software follow cautiously the numerical methods developed by the scientific community. Even though the phase-field method is not a default option in Abaqus, the code proposes a unique way to implement and test complex, extraneous models. In the last five years, phase-field fracture models in Abaqus have gained unbelievable popularity among scientists and engineers alike. However, most implementations are based on the quadratic crack representation function, which is easy to solve but has no elastic threshold. Various solutions have been proposed as a workaround to implement the linear damage function, however, none of them obtain consistent results to the original Griffith solution when the length scale is reduced to zero. This paper presents an energetically consistent linear damage gradient model in Abaqus. The bound constrained optimization is achieved using Lagrange multipliers as an additional degree of freedom. We show that when the necessary energy corrections are applied, the phase-field simulations are in agreement with the analytical results of linear elastic fracture mechanics. Furthermore, through elaborate benchmark tests, we verified our code and experimentally demonstrated the validity of our implementation.