According to the Mishna on our daf, if the person is traveling for personal reasons, he should really go home and destroy the hametz properly. If, however, the trip was for a mitzva – like to sacrifice the korban Pesah, to perform a circumcision on his son or to attend the celebration of a wedding at his in-laws’ home – then, if he cannot return home to destroy the hametz, he is allowed to do bitul ba-lev, to nullify the hametz in his heart.
The Jerusalem Talmud points out that we learn from this Mishna how important it is to keep peace within the family, since the Mishna chooses to categorize attendance at a family wedding celebration together with circumcision and the Passover sacrifice as important mitzvot.
The Gemara uses this line in the Mishna as a springboard for a wide-ranging discussion of celebrations and marriage. One baraita quoted by the Gemara encourages a person to sell all of his worldly possessions in order to arrange to marry the daughter of a Torah scholar or to arrange for his daughter to marry a Torah scholar. The baraita then gives a metaphor:
This type of marriage can be compared to grapes of a vine that become intertwined with grapes of a vine, something which is beautiful and acceptable to God and man. And one should not marry the daughter of an ignoramus. This type of marriage can be compared to grapes of a vine that have become intertwined with berries of a bramble, which is something unseemly and unacceptable.
The sneh, which is also referred to in the Talmud as vardina, is, apparently, what is known today as the bramble or Rubus Sanctus, a crawling or climbing plant that grows wild, usually on river banks or other damp places throughout Israel. The plant has leaves, many sharp thorns and white or purple flowers of about 2 centimeters in diameter. It also has berries – referred to by the baraita as invei ha-sneh – which are edible, although they are usually small and have little juice in them.