To form the negative command for 2nd person with irregular mujarrad (bare) verbs, you will do two things:
1.Put لا in front of the 2nd person present tense
2.Make the ending majzoom
One of the main principles with irregular verbs is the principle that two sakin letters (letters with sukoon) can NOT be beside each other. Whenever this will be the case, one of the sakin letters is dropped.
We will look at mujarrad muda’af (double letter) verbs first. Example (2nd person present tense of صَبَّ – to pour)
تَصُبُّ you (m.sg) are pouring
تَصُبُّيْنَ you (f.pl) are pouring
تَصُبُّوْنَ you (m.pl) are pouring
تَصْبُبْنَ you (f.pl) are pouring
Note: the 2nd person feminine plural present tense does not change, ever.
Now, looking at تَصُبُّ – remember that a letter with shaddah over it is really a double letter, so بّ is really بْ + بُ . So if we put a sukoon on the ending of تصبّ as is usually done in the majzoom case (for singular), two sakin letters will meet:
بْ + بْ and since we are not allowed to do this, we will instead change the dammah to fat-hah to avoid the meeting of two sakin letters:
لا تَصُبَّ Don’t pour! (m.sg)
The other forms are easier, we just drop the noon:
لا تصبِّيْ Don’t pour! (f.sg)
لا تصبُّوا Don’t pour! (m.pl)
لا تصْبُبْنَ Don’t pour! (f.pl)
And the feminine plural does not change, as we mentioned, but notice how the double letter comes apart just like in some of the past tense forms (like صَبَبْتُ – I poured)
For mazeed (increased) verbs that are muda’af, the same principles apply. Example for أَعِدَّ (wazn IV) – to prepare something
لا تُعِدَّ Don’t prepare! (m.sg)
لا تُعِدِّيْ Don’t prepare! (f.sg)
لا تُعِدُّوا Don’t prepare! (m.pl)
لا تُعْدِدْنَ Don’t prepare! (f.sg)
This is how it is for most of the wazns (patterns). However, patterns II and V of a double letter are conjugated like a regular verb. Example:
حَقَّقَ (whose root is حَقَّ )
لا تُحَقِّقْ Don’t bring about (actualize)….! (m.sg)
لا تَشَدَّدْ Don’t be harsh! (m.sg) (from the root شَدَّ )
As for verbs with a weak middle letter, then we form the negative command thusly:
لا تَقُلْ Don’t say! (m.sg) The wow is dropped to avoid the meeting of two sakin letters (لا تَقُوْلْ )
لا تَقُوْلِيْ Don’t say! (f.sg) The wow is not dropped because there is no meeting of two sakin letters
لا تَقُوْلُوا Don’t say! (m.pl) The wow is not dropped because thereis no meeting of two sakin letters
لا تَقُلْنَ Don’t say! (f.pl) The wow is dropped to avoid the meeting of two saakin letters (لا تَقُوْلْنَ )
Apply this principle to each of the three types of weak middle letter verbs for the mujarrad (bare):
لا تَنَمْ Don’t sleep! (m.sg) The weak middle letter- in this case it is alif- is dropped (لا تَنَاْمْ )
لا تَبِعْ Don’t sell! (m.sg) The weak middle letter- yaa- is dropped (لا تَبِيْعْ )
The same principle applies for mazeed (increased) verbs with a weak middle letter (except for wazns II and V which form the negative command like a regular verb). Example is the wazn IV verb أشَارَ ، يُشِيْرُ to point:
لا تُشِرْ Don’t point! (m.sg) Yaa is dropped (لا تُشِيْرْ )
لا تُشِيْرِيْ Don’t point! (f.sg) Noon is dropped
لا تُشِيْرُوا Don’t point! (m.pl) Noon is dropped
لا تُشِرْنَ Don’t point (f.pl) No change ( the present tense تُشِرْنَ was تُشِيْرْنَ but a yaa was dropped because of the meeting of the two sakin letters)
As for verbs with a weak last letter, then the negative command for them is formed thusly:
لا تَبْكِ Don’t cry (m.sg) Yaa was dropped (from تَبْكِيْ )
لا تَبْكِيْ Don’t cry (f.sg) Noon was dropped (from تَبْكِيْنَ ) as is the normal case for 2nd person feminine singular
لا تَبْكُوا Don’t cry (m.pl) Noon was dropped ( from تَبْكُوْنَ ) as is the normal case for 2nd person masculine plural
لا تَبْكِيْنَ Don’t cry (f.pl) No change, as is normal for the 2nd person f. pl.
Apply the same principle to all three types of weak end letter verbs which are mujarrad (bare):
لا تَنْسَ Don’t forget! (m.sg) Dropped the yaa (from لا تَنْسَى )
لا تَنْسَيْ Don’t forget! (f.sg) Dropped the noon, as is the normal case
لا تَنْسَوا Don’t forget! (m.pl) Dropped the noon, as is the normal case
لا تَنْسَيْنَ Don’t forget! (f.pl) No change, as is the normal case
لا تَشْكُ Don’t complain! (m.sg) Dropped the wow (from تَشْكُوْ )
لا تَشْكِيْ Don’t complain! (f.sg) Dropped the noon, as is the normal case
لا تَشْكُوا Don’t complain! (m.pl) Dropped the noon, as is the normal case
لا تَشْكُوْنَ Don’t complain! (f.pl) No change, as is the normal case
Review weak middle and end letter conjugations for mujarrad verbs in chapters 27 and 28 of Madinah Book 2
http://old.iu.edu.sa/spages/edu/syukbah/du2_29.htm
Apply the same principles to mazeed (increased ) verbs (including wazns II and V ). For سَمَّى، يُسَمِّيْ (II) to name/call
لا تُسَمِّ Don’t name! (m.sg) Dropped the yaa (from تُسَمِّيْ )
لا تُسَمِّيْ Don’t name! (f.sg) Dropped the noon, as is the normal case
لا تُسَمُّوا Don’t name! (m.pl) Dropped the noon, as is the normal case
لا تُسَمِّيْنَ Don’t name! (f.pl) No change, as is the normal case
تَغَدَّى، يَتَغَدَّى (V) to have lunch
لا تَتَغَدَّ Don’t have lunch! (m.sg) Dropped the yaa (from تَتَغَدَّى )
لا تَتَغَدَّيْ Don’t have lunch! (f.sg) Dropped the noon, as is the normal case
لا تَتَغَدَّوا Don’t have lunch! (m.pl) Dropped the noon, as is the normal case
لا تَتَغَدَّيْنَ Don’t have lunch! (f.pl) No change, as is the normal case
All the daals د in the above forms have fat-hah.
اِشْتَرَى،يَشْتَرِيْ (VIII) to buy
لا تَشْتَرِ Don’t buy! (m.sg) Dropped the yaa (from تَشْتَرِيْ ) raa has kasrah
لا تَشْتَرِيْ Don’t buy! (f.sg) Dropped the noon, as is the normal case
لا تَشْتَرُوا Don’t buy! (m.pl) Dropped the noon, as is the normal case
لا تَشْتَرِيْنَ Don’t buy! (f.pl) No change, as is the normal case