✅Answer: Please consider the following narration:

1⃣فِی الْمَجَالِسِ وَ عُیُونِ الْأَخْبَارِ عَنْ مُحَمَّدِ بْنِ عَلِیٍّ مَاجِیلَوَیْهِ عَنْ عَلِیِّ بْنِ إِبْرَاهِیمَ عَنْ أَبِیهِ عَنِ الرَّیَّانِ بْنِ شَبِیبٍ قَالَ دَخَلْتُ عَلَی الرِّضَا فِی أَوَّلِ یَوْمٍ مِنَ الْمُحَرَّمِ فَقَالَ لِی یَا ابْنَ شَبِیبٍ أَ صَائِمٌ أَنْتَ فَقُلْتُ لَا فَقَالَ إِنَّ هَذَا الْیَوْمَ هُوَ الْیَوْمُ الَّذِی دَعَا فِیهِ زَکَرِیَّا رَبَّهُ فَقَالَ رَبِّ هَبْ لِی مِنْ لَدُنْکَ ذُرِّیَّةً طَیِّبَةً إِنَّکَ سَمِیعُ الدُّعاءِ فَاسْتَجَابَ اللَّهُ لَهُ وَ أَمَرَ الْمَلَائِکَةَ فَنَادَتْ زَکَرِیَّا وَ هُوَ قائِمٌ یُصَلِّی فِی الْمِحْرابِ أَنَّ اللَّهَ یُبَشِّرُکَ بِیَحْیی فَمَنْ صَامَ هَذَا الْیَوْمَ ثُمَّ دَعَا اللَّهَ عَزَّ وَ جَلَّ اسْتَجَابَ اللَّهُ عَزَّ وَ جَلَّ لَهُ کَمَا اسْتَجَابَ لِزَکَرِیَّا الْحَدِیثَ

📚Uyun Akhbar al-Ridha, Vol. 1, p. 299

Translation: Rayan ibn Shabib says: On the first day of Muharram, I visited Imam Ridha (AS), and the Imam asked, 'O son of Shabib, are you fasting?' I replied, 'No.' He said: 'Today is the day when Zakariya (AS) called upon his Lord, saying: 'O my Lord, grant me a righteous offspring from Yourself. Indeed, You are the One who hears prayers.' Then Allah answered his prayer and commanded the angels to call out to Zakariya while he was in his prayer niche: 'Indeed, Allah gives you the glad tidings of Yahya (John).' So, whoever fasts on this day and calls upon Allah, Allah will answer their prayers, just as He answered Zakariya's prayer.'

Explanation: As the narration indicates, this applies to all needs, and we can pray both for a child and for other needs.

Suggestion: Insha'Allah, let us fast on the first day of Muharram and then pray for the hastening of the appearance of our Master, may Allah bless him.

اللَّهُمَّ فَصَلِّ عَلَی مُحَمَّدٍ وَ آلِ مُحَمَّدٍ وَ عَجِّلْ لِوَلِیِّکَ الْفَرَجَ وَ الْعَافِیَةَ وَ النَّصْرَ