As part of Solomon's expository on the meaning and purpose of life he emphasizes here that quiet reflection is more profitable the being in a constant state of mindless jubillance (see Eccl 2:2). The Epicurean attitude that is so prevalent now is discouraged by one who could afford to experience it all. It is thus important to consider the purpose of life as stated at Eccl. 12:13,14- "....fear the true God and keep his commandments. For this is the whole obligation of man....".
And here is the verse! It is indeed in the bible
A good name is better than precious ointment, and the day of death than the day of birth. It is better to go to the house of mourning than to go to the house of feasting, for this is the end of all mankind, and the living will lay it to heart. Sorrow is better than laughter, for by sadness of face the heart is made glad. The heart of the wise is in the house of mourning, but the heart of fools is in the house of mirth.
The only occasion celebrating death I am aware of is Good Friday where we celebrate Christ's sacrifice on the cross. This is a Christian tradition and not a biblical holy day/feast day.
15 Rejoice with them that do rejoice, and weep with them that weep.