измени свой HTML, как это
<div class=" d-table w-100">
<p class="d-table-cell">بِسْمِ ٱللَّهِ ٱلرَّحْمَٰنِ ٱلرَّحِيمِ</p>
<div class="d-table-cell tar w-10">
<audio id="player2" src="http://www.mp3naat.com/download/owais-raza-qadri/mustafa-jaan-e-rehmat.mp3"></audio>
<a id="toggle-button"><i id="icons" class="fa fa-play-circle-o fa-2x"></i></a>
</div>
</div>
и JavaScript
<script>
var count =0;
document.getElementById("toggle-button").onclick = function() {
console.log("hello");
if(count%2==0){
document.getElementById("player2").play();
document.getElementById("icons").classList.remove("fa-play-circle-o");
document.getElementById("icons").classList.add("fa-pause-circle-o");
}else{
document.getElementById("player2").pause();
document.getElementById("icons").classList.add("fa-play-circle-o");
document.getElementById("icons").classList.remove("fa-pause-circle-o");
}
count++;
}
</script>