Asalam Alaikum ya Sheik.
Please a friend of mine and his family has just moved to Germany. Currently the Sun rises by 3am and sets by 10pm.
Are they permitted to shorten their fast ?

Ustadh Abdulganiy Jumah: Wa alaykum salām wa rahmatullah.
There is no evidence that says fasting period should be so and so hours. As long as there is appearance of fajr and sunset, one has to fast it even if the day lasts four 23 hours.
However, if one tries it and it is unbearable for one, then one can fast it some other time.
However, if there is no sunset at all or no sunrise at all as it happens is some Scandinavian countries, then one can use the timing of the closest place to one’s country that still experiences day and night.
Wallahu a’lam.