\[ \boxed { aby \left ( x \right ) \left ( -1+y \left ( x \right ) \right ) {\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left ( x \right ) - \left ( \left ( 2\,ab-a-b \right ) y \left ( x \right ) + \left ( 1-a \right ) b \right ) \left ( {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) \right ) ^{2}+fy \left ( x \right ) \left ( -1+y \left ( x \right ) \right ) {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) =0} \]
Mathematica: cpu = 1.296165 (sec), leaf count = 98 \[ \left \{\left \{y(x)\to \text {InverseFunction}\left [-\frac {a \text {$\#$1}^{\frac {1}{a}} \left ((a+1) \, _2F_1\left (\frac {1}{a},-\frac {1}{b};1+\frac {1}{a};\text {$\#$1}\right )+\text {$\#$1} \, _2F_1\left (1+\frac {1}{a},\frac {b-1}{b};2+\frac {1}{a};\text {$\#$1}\right )\right )}{a+1}\& \right ]\left [\int _1^x c_1 e^{-\int _1^{K[3]} \frac {f(K[1])}{a b} \, dK[1]} \, dK[3]+c_2\right ]\right \}\right \} \]
Maple: cpu = 1.669 (sec), leaf count = 46 \[ \left \{ {\it \_C1}\,{{\rm e}^{-{\frac {fx}{ab}}}}-{\it \_C2}+\int ^{y \left ( x \right ) }\!{\frac {\sqrt [a]{{\it \_a}}\sqrt [b]{{\it \_a}-1 }}{{\it \_a}\, \left ( {\it \_a}-1 \right ) }}{d{\it \_a}}=0 \right \} \]