Cross my heart and swear to die!

The word of a person of substance is their bond and this is only right and proper. After all, we are judged by the extent to which we keep our promises. The validity of an oral contract however, hinges on the level of mutual trust - or lack thereof. It is a brittle thing the unwritten agreement and these days, it is almost foolhardy, to enter such an understanding. Foolhardy because of the short supply of trust and 'almost' because it nags at our better self that we are rarely able to accept or honor unwritten contracts.
This is a sign of the times. Why, even the institution of marriage has several sheets of paperwork - not to mention the now routine pre-nuptial agreements. In contrast to these legally binding documents, there is an interesting social dynamism observed in relationships that have unwritten agreements between or among them.
First, let's take a second to study the relatively simpler relationships at work between individuals who have binding agreements. Your second is up, because there is hardly any dynamism. Party A has put their John Hancock to do or not do a certain something to, for, with Party B. Written agreements are impersonal and some would even say dilute and destroy relationships that were just fine before the written contract was concluded. However, the written contract, with its inherent clarity - eliminates the "what if" factor and reassures both sides. On the other hand the "what if" factor preoccupies the relationship of verbal contracts to the extent that every little incident is put under the microscope… Unwritten agreements are like a house built on a foundation of sand.
My personal view is that I would not enter unwritten agreements of which the potential fallout in case of a double cross will exceed ETB 100. Anything more - employment, recruiting staff, bank transactions, and yes - marriage and its flip side, must be signed and notarized - in triplicate!
What is really at stake here is that the world we live in is becoming less of a trust based society and one in which litigation is the rule rather than the exception. The good old days when all that was required to seal a deal was a firm handshake are long gone. Gritty reality has set in and only the very stupid or the extravagantly rich would indulge in an unwritten contract.
The unwritten contract is the bane of lawyer types as it is on the back of the inked agreement that they make a living - which reminds us of another potentially dangerous consequence of oral agreements. When such a gentleman's contract is abrogated by one or both parties, there is virtually no recourse for the aggrieved. Lacking legal grounds to right the wrong, the injured party may resort to taking matters into their own hands - often violently.
At this point though, we must mention the great Ethiopian institution of mediation by elders. Even without a written agreement and possibly without the presence of the original witnesses (if any), it is possible to appeal to the larger community for redress.