• لُمَّ
• لَّمّ
• لَّمَم

Appears 4 times in the Quran.

1. 6:150 قُلْ هَلُمَّ شُهَدَآءَكُمُ ٱلَّذِينَ يَشْهَدُونَ أَنَّ ٱللَّهَ حَرَّمَ هَٰذَا فَإِن شَهِدُوا۟ فَلَا تَشْهَدْ مَعَهُمْ وَلَا تَتَّبِعْ أَهْوَآءَ ٱلَّذِينَ كَذَّبُوا۟ بِـَٔايَٰتِنَا وَٱلَّذِينَ لَا يُؤْمِنُونَ بِٱلْءَاخِرَةِ وَهُم بِرَبِّهِمْ يَعْدِلُونَ

   Say: Bring your witnesses who should bear witness that Allah has forbidden this, then if they bear witness, do not bear witness with them; and follow not the low desires of those who reject Our communications and of those who do not believe in the hereafter, and they make (others) equal to their Lord.
   

2. 33:18 قَدْ يَعْلَمُ ٱللَّهُ ٱلْمُعَوِّقِينَ مِنكُمْ وَٱلْقَآئِلِينَ لِإِخْوَٰنِهِمْ هَلُمَّ إِلَيْنَا وَلَا يَأْتُونَ ٱلْبَأْسَ إِلَّا قَلِيلًا

   Allah knows indeed those among you who hinder others and those who say to their brethren: Come to us; and they come not to the fight but a little,
   

3. 53:32 ٱلَّذِينَ يَجْتَنِبُونَ كَبَٰٓئِرَ ٱلْإِثْمِ وَٱلْفَوَٰحِشَ إِلَّا ٱللَّمَمَ إِنَّ رَبَّكَ وَٰسِعُ ٱلْمَغْفِرَةِ هُوَ أَعْلَمُ بِكُمْ إِذْ أَنشَأَكُم مِّنَ ٱلْأَرْضِ وَإِذْ أَنتُمْ أَجِنَّةٌ فِى بُطُونِ أُمَّهَٰتِكُمْ فَلَا تُزَكُّوٓا۟ أَنفُسَكُمْ هُوَ أَعْلَمُ بِمَنِ ٱتَّقَىٰٓ

   Those who keep aloof from the great sins and the indecencies but the passing idea; surely your Lord is liberal in forgiving. He knows you best when He brings you forth from the earth and when you are embryos in the wombs of your mothers; therefore do not attribute purity to your souls; He knows him best who guards (against evil).
   

4. 89:19 وَتَأْكُلُونَ ٱلتُّرَاثَ أَكْلًا لَّمًّا

   And you eat away the heritage, devouring (everything) indiscriminately,