Safe value must use [property]=binding after bypass security with DomSanitizer

You need to sanitize() the safevalue like this :

this.domSanitizer.sanitize(SecurityContext.HTML,this.domSanitizer.bypassSecurityTrustHtml(this.parishDetail.mass_timings));

As the error message says, the sanitized HTML needs to be added using property binding:

<p [innerHTML]="massTimingsHtml"></p>

constructor(private domSanitizer:DomSanitizer) {
  this.massTimingsHtml = this.getInnerHTMLValue();
}
getInnerHTMLValue(){
  return this.domSanitizer.bypassSecurityTrustHtml(this.parishDetail.mass_timings);
}

StackBlitz example (based on Swapnil Patwa's Plunker - see comments below)