  In this paper, we prove two supercongruences by the Wilf-Zeilberger method.
One of them is, for any prime $p>3$, \begin{align*}
\sum_{n=0}^{(p-1)/2}\frac{3n+1}{(-8)^n}\binom{2n}n^3\equiv
p\left(\frac{-1}p\right)+\frac{p^3}4\left(\frac2p\right)E_{p-3}\left(\frac14\right)\pmod{p^4},
\end{align*} where $\left(\frac{\cdot}p\right)$ stands for the Legendre symbol,
and $E_{n}(x)$ are the Euler polynomials. This congruence confirms a conjecture
of Sun \cite[(2.18)]{sun-numb-2019} with $n=1$.
