Rule 1: 1. عَلَيْكَ أَنْ 'you must'
Obligation is expressed with عَلَى and a pronoun suffix, literally upon you is to ...: عَلَيْكَ أَنْ تَذْهَبَ you must go, عَلَيْنَا أَنْ نُسَاعِدَهُمْ we must help them. The preposition takes the form عَلَيْـ before suffixes (عَلَيْهِ, عَلَيْهِمْ, عَلَيْكُمْ). After a condition or a topic the phrase begins with فَـ: إِنَّ الْحُجَّاجَ ضُيُوفُ اللّٰهِ فَعَلَيْكُمْ أَنْ .... A noun may replace the أَنْ clause: عَلَيْكَ الصَّبْرُ you must be patient. The negative you need not is لَيْسَ عَلَيْكَ أَنْ.
عَلَيْكُمْ أَنْ تَجْتَمِعُوا حَوْلَ بَيْتِ اللّٰهِ.
ʿalaykum an tajtamiʿū ḥawla bayti llāhi
You must gather around the House of God.
اَلْحُجَّاجُ ضُيُوفُ اللّٰهِ، فَعَلَيْنَا أَنْ نَخْدُمَهُمْ.
al-ḥujjāju ḍuyūfu llāhi, fa-ʿalaynā an nakhdumahum
The pilgrims are God's guests, so we must serve them.
عَلَيْكَ أَنْ تُسَاعِدَ أَبَاكَ يَا بُنَيَّ.
ʿalayka an tusāʿida abāka yā bunayya
You must help your father, my son.
لَيْسَ عَلَيْكِ أَنْ تَحْمِلِي الْمَاءَ وَحْدَكِ.
laysa ʿalayki an taḥmili l-māʾa waḥdaki
You (f.) need not carry the water by yourself.
عَلَيْهِمُ الطَّاعَةُ وَعَلَى الزَّعِيمِ الْعَدْلُ.
ʿalayhimu ṭ-ṭāʿatu wa-ʿala z-zaʿīmi l-ʿadlu
Obedience is their duty, and justice the leader's.