<small>
Posted: {{ $post->created_at ? $post->created_at->diffForHumans() : 'Unknown time' }}
</small>
use this in blade view like this
<h1>{{$post->title}}</h1>
<h5>{{$post->content}}</h5>
<small>
Posted: {{ $post->created_at ? $post->created_at->diffForHumans() : 'Unknown time' }}
</small>