Let \(\mathcal {A}(n)\) denote the \((1,n)\text {-th}\) Fourier coefficient of a \(\text {SL}(3, \mathbb {Z})\) Hecke eigenform or the ternary divisor function \(d_3(n)\) . Let Q(x, y) be a symmetric positive definite quadratic form. This article establishes an asymptotic formula with a power-saving error term for the following sum \(\begin{aligned} \sum _{1 \leqslant m \leqslant X} \sum _{1 \leqslant n\leqslant Y} \mathcal {A}(Q(m,n)), \end{aligned}\) where \(X>1\) and \(Y\leqslant X\) .