He owes zakaah for trade goods but he doesn’t have any cash.

A person owns a piece ofland and one year has passed since he
acquiredit. Zakaah is due becauseit comes under the heading of trade
goods (i.e., he bought it in order to sell it). How should he pay
zakaah onit? Please note that he only has a little cash, very little.
Praise be to Allaah.
Zakaah is due on trade goods according to the Qur'aan and Sunnah.
In the Qur'aan this is indicated by the general meaning of the verse
in which Allaah says (interpretation of the meaning):
"O you who believe! Spend of the good things which you have (legally)
earned, and of that which We have produced from the earthfor you"
[al-Baqarah 2:267]
Mujaahid said: "Spend ofthe good things which you have (legally)
earned" means trade.
With regard to evidence form the Sunnah, Abu Dawood narrated
(1562)that Samurah ibn Jundub said: The Messenger of Allaah (peace and
blessings of Allaah be upon him) used to command us to give zakaah
from that which we had prepared for sale.
The isnaad of this hadeeth is subject to some discussion, but some of
the scholars classed it as hasan, such as Ibn 'Abd al-Barr (may Allaah
have mercy on him), and it is the view that the scholars of the
Standing Committee for Issuing Fatwas adopted.
See Fataawa al-Lajnah al-Daa'imah, 9/331.
Zakaah is due on things that have been preparedfor trade if they reach
the nisaab (minimum threshold) and one year has passed (since they
were acquired).
Based on this, zakaah must be paid on the landwhich has been in your
possession for a year; you have to determine the value of the land at
the end of the year, and pay one-quarter of ten percent. So if its
value is one hundred thousand (100,000) dinars, for example, you have
to pay zakaah of 2.5% or two and a half thousand (2,500), and so on.,
If you have cash, then you must pay it and it is not permissible to
delay paying zakaah until the land is sold. But if you donot have cash
with which to pay the zakaah,then it becomes a debt that you owe and
must be paid when it becomes possible to do so. If you cannot do it
until you sell the land, then you have to pay zakaah from the price
you receive for the land for each year in which zakaah was due.
Shaykh Ibn Baaz (may Allaah have mercy on him) said:
Zakaah is due on land that is prepared for trade. The evidence for
that is the well known hadeeth of Samurah ibn Jundub (may Allaah be
pleased with him) who said: The Messenger of Allaah (peace and
blessings of Allaah be upon him) used to command us to give zakaah
from that which we had prepared for sale.
He also said:
If land and other similar things such as houses and cars etc are
prepared for sale, then you must pay zakaah on them each year
according to their value, when one full year has passed. It is not
permissible to delay that, except in the case of one who is unable to
pay the zakaah on them because he does not have any other wealth. Then
he may be given a respite until he sells it and pays the zakaah for
all the years, each year according to its value at the end of that
year, regardless of whether the value is more than the price he gets
for it oris less that the price for which he bought the land, car or
house.
Majmoo' Fataawa Ibn