Male boomslang.. 99.99% sure
I can't see the eyes, were they large and black? Also can't see the tip of the tail, was it long and thin like a pencil lead? If so, then 100% boomslang.
I've got a few resident ones around my home including a large male that I see every year a few times, if you see the snakes are active, then birds will be and so will the fish I've noticed
There are a lot of colour variations on the boomslang but that is a typical one for the males..They will lose the bright blues and turquoises as they get older and be more yellow and black like that.. Those when they are middle aged and have all the colour range, are the most beautiful snakes I've seen, hands down. If he was by your home, he would have been there all the time, that one is at least 2 years old based on what I've seen with the ones around me. The birds let you know whenever they are around, and if you are mates with your resident birds, they will come call you for assistance to chase them away.. You can get an idea of your resident ones as they have quite a small home range, my large male is seen over only a range of maybe 100 x 50 m and I have a large green female and a large brown female that live around the home area, every year I see the babies around the house. They won't generally bother you and are very passive.