What Is The Ruling on the One Who Didn’t Slaughter his Sacrifice Until the 11th Day of Dhu al Hijjah?

All praise be to Allah, this point that you referred to, which is his saying: “He asked me to make Hajj on behalf of the two of them.”. He may have made Hajj on behalf of one of them, but if he performed Hajj on behalf of both of them in one pilgrimage, then it is not permissible. That’s because one ritual/pilgrimage cannot be divided; it must be on behalf of one person (i.e., only). So, for example, if a person wants to perform Hajj on behalf of his mother and father in one year with a single ritual/pilgrimage, then that is not permissible. Rather, he should only make Hajj on behalf of his father or mother in one year and on behalf of the second parent in another year. As for what he did in delaying the slaughtering to the second day and shaving on the first day, this is fine. That is because on the day of Eid, one should arrange the rituals, that are done in it, as follows: First, he starts with throwing the stones of al-Aqabah. Then, he slaughters his sacrifice. Then, he shaves his head or trims it, and shaving is better. Then, he goes down to Makkah, performs the Tawaf of al-Ifadah, which is the Tawaf of Hajj, performs the Sa’iy (going back and forth) between (the two mountains) al-Safa and al-Marwa if he was performing Tamattu’, Qiran, or Ifrad and hadn’t performed Sa’iy after the Tawaf of Arrival. So, if he was performing Qiran or Ifrad and had performed Sa’iy after the Tawaf of Arrival, then he would not repeat the Sa’iy a second time.