q-Pfaff-Saalschütz sum

A q-analog of the Saalschütz theorem due to Jackson is given by _3 ϕ_2(q^(-n), a, b;c;a b/(c q^(n - 1));q, q) = ((c/a;q)_n (c/b;q)_n)/((c;q)_n (c/(a b);q)_n), where _3 ϕ_2 is the q-hypergeometric function.