Is it recommended for a father not to look at the 'aqiqah of his son when it is being slaughtered, and what is the legal proof for that?

The statement that it is preferable for a father not to look at the 'aqiqah of his son when slaughtering it has no basis, and there is no harm in him looking at it. If that were true, the father would have been required to appoint someone else to slaughter it, and that has not been narrated. Moreover, if he slaughters it himself, he will not be able to avoid looking at it.